Czech Republic's tennis player Petra Kvitova poses for a picture with her coaches during a news conference, after she was injured on Tuesday when she fought off an intruder in her home, damaging all the fingers on her playing hand, in Prague, Czech Republic December 23, 2016. REUTERS/David W Cerny 

Football Soccer Britain - Liverpool v West Ham United - Premier League - Anfield - 11/12/16 West Ham United manager Slaven Bilic talks to Andy Carroll as he is about to be substituted on Action Images via Reuters / Lee Smith Livepic EDITORIAL USE ONLY. No use with unauthorized audio, video, data, fixture lists, club/league logos or "live" services. Online in-match use limited to 45 images, no video emulation. No use in betting, games or single club/league/player publications. Please contact your account representative for further details. 

Republican U.S. presidential nominee Donald Trump gives a fist-pump to the ground crew as he arrives on his plane in St. Augustine, Florida, U.S. October 24, 2016. REUTERS/Jonathan Ernst 

U.S. President Barack Obama gives a fist-bump to a robotic arm operated by Nathan Copeland, a quadriplegic brain implant patient who can experience the sensation of touch and control a remote robotic arm with his brain during a tour of the innovation projects at the White House Frontiers conference in Pittsburgh, U.S. October 13, 2016. REUTERS/Carlos Barria 

Golf Britain - Alfred Dunhill Links Championship - Old Course St. Andrews, Scotland - 8/10/16
England's Danny Willett and Jonathan Smart celebrate on the first green during the third round
Action Images via Reuters / Lee Smith
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Philippine President Rodrigo Duterte gestures with "fist bump", his May presidential campaign election gesture, as he poses with soldiers at the military's Scout Ranger Camp Tecson in San Miguel, Bulacan in northern Philippines September 15, 2016. REUTERS/Erik De Castro 

Soldiers gesture "fist bump", Philippine President Rodrigo Duterte's May presidential election campaign gesture at the military's Scout Ranger Camp Tecson in San Miguel, Bulacan in northern Philippines September 15, 2016. REUTERS/Erik De Castro 

Philippine President Rodrigo Duterte gestures with "fist bump", his May presidential campaign election gesture, as he poses with soldiers at the military's Scout Ranger Camp Tecson in San Miguel, Bulacan in northern Philippines September 15, 2016. REUTERS/Erik De Castro 

Britain Cricket - England v Pakistan - Third One Day International - Trent Bridge - 30/8/16
England's Jos Buttler and Eoin Morgan celebrate
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Barron Trump (L) bumps a fist with Donald Trump Jr. as Melania Trump watches at the Republican National Convention in Cleveland, Ohio, U.S., July 21 2016. REUTERS/Carlo Allegri

Barron Trump (L) bumps a fist with Donald Trump Jr. as Melania Trump watches at the Republican National Convention in Cleveland, Ohio, U.S., July 21 2016. REUTERS/Carlo Allegri

Golf - British Open - Practice Round - Royal Troon, Scotland, Britain - 11/07/2016
Byeong Hun An of South Korea (L) fist bumps his compatriot Seung Yul Noh as they walk across the 11th green during practice
REUTERS/Craig Brough
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Joshua Zepeda (R) greets another supporter after posing for a picture while attending a rally for U.S. Democratic presidential candidate Bernie Sanders in Vista, California, United States, May 22, 2016. REUTERS/Mike Blake

Former U.S. President George W. Bush fist bumps wounded warrior Master Sergeant Israel Del Toro Jr, who sports a "Stay Strong" tattoo, on stage during the Symposium on Invisible Wounds at the Invictus Games in Orlando, Florida, U.S., May 8, 2016. REUTERS/Carlo Allegri 

Former U.S. President George W. Bush fist bumps wounded warrior Master Sergeant Israel Del Toro Jr on stage during the Symposium on Invisible Wounds at the Invictus Games in Orlando Florida, U.S., May 8, 2016. REUTERS/Carlo Allegri TPX IMAGES OF THE DAY

Football Soccer - Manchester City v Real Madrid - UEFA Champions League Semi Final First Leg - Etihad Stadium, Manchester, England - 26/4/16
Real Madrid's Gareth Bale shakes hands with Casemiro after the game
Reuters / Phil Noble
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Syrian refugee Suhila (L), 50, plays with Couds before an interview with Reuters at the Sant'Egidio community in Rome, Italy, April 20, 2016. REUTERS/Max Rossi 

Alpine Skiing - Alpine Skiing World Cup - Men's Slalom World Cup victory ceremony - St. Moritz, Switzerland - 20/3/16 - Marcel Hirscher of Austria and Henrik Kristoffersen of Norway react REUTERS/Arnd Wiegmann

Alpine Skiing - Alpine Skiing World Cup - Women's Giant Slalom race 2nd run - St. Moritz, Switzerland - 20/3/16 - Viktoria Rebensburg of Germany and Eva Maria Brem of Austria react REUTERS/Arnd Wiegmann

Cricket - South Africa v England - World Twenty20 cricket tournament - Mumbai, India, 18/03/2016. South Africa's Jean-Paul Duminy (L) is congratulated by his teammate David Miller after scoring his half century as England's Chris Jordan looks on. REUTERS/Danish Siddiqui 

Team Alberta skip Kevin Koe (R) bumps fists with lead Ben Hebert (L) as second Brent Laing (2nd L) and third Marc Kennedy watch after defeating Team Newfoundland and Labrador during their gold medal game at the Brier curling championships in Ottawa, Canada, March 13, 2016. REUTERS/Chris Wattie TPX IMAGES OF THE DAY

Denver Broncos' quarterback Peyton Manning pumps fists with Broncos President and General Manager John Elway (L) after the Broncos defeated the Carolina Panthers in the NFL's Super Bowl 50 football game in Santa Clara, California February 7, 2016. REUTERS/Mike Blake 

Football Soccer - Port Vale v Coventry City - Sky Bet Football League One - Vale Park - 7/2/16
Port Vale?s Sam Kelly and Coventry?s Jacob Murphy at the end of the match
Mandatory Credit: Action Images / Andrew Boyers
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Republican U.S. presidential candidate Senator Marco Rubio gets a fist bump from one of his sons after speaking to supporters at the Rubio caucus watch party at the Downtown Marriott Hotel in Des Moines, Iowa February 1, 2016. REUTERS/Aaron P. Bernstein

Former U.S. President Bill Clinton gets a fist bump as he arrives to introduce U.S. Democratic presidential candidate Hillary Clinton at a "Get Out to Caucus" rally in Cedar Rapids, Iowa January 30, 2016. REUTERS/Brian Snyder 

Former U.S. Republican presidential candidate Senator Lindsey Graham (L) fist bumps his former rival and current Republican presidential candidate Senator Marco Rubio (R) as they wait on the floor of the House of Representatives before the start of U.S. President Barack Obama's State of the Union address to a joint session of Congress in Washington, January 12, 2016. REUTERS/Jonathan Ernst

U.S. Republican presidential candidate Senator Marco Rubio (C) fist bumps former rival candidate Senator Lindsey Graham (R) as former Republican presidential nominee Senator John McCain (L) looks on as they wait on the floor of the House of Representatives before the start of U.S. President Barack Obama's State of the Union address to a joint session of Congress in Washington, January 12, 2016. REUTERS/Carlos Barria 

Lieutenant Sam Robinson, a public information officer at San Quentin State Prison, bumps fists with a guard at the entrance to the East Block for condemned prisoners during a media tour of California's Death Row in San Quentin, California December 29, 2015. REUTERS/Stephen Lam 

Tennis - Great Britain v Australia - Davis Cup Semi Final - Emirates Arena, Glasgow, Scotland - 19/9/15
Men's Doubles - Great Britain's Andy Murray (L) and Jamie Murray bump fists during their match
Action Images via Reuters / Jason Cairnduff
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Tennis - Great Britain v Australia - Davis Cup Semi Final - Emirates Arena, Glasgow, Scotland - 19/9/15
Men's Doubles - Great Britain's Andy Murray (R) and Jamie Murray bump fists during their match
Action Images via Reuters / Jason Cairnduff
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Football - Bolton Wanderers v Wolverhampton Wanderers - Sky Bet Football League Championship - Macron Stadium - 12/9/15
Bolton Wanderers manager Neil Lennon (R) celebrates after the final whistle
Mandatory Credit: Action Images / Craig Brough
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Hockey - Unibet EuroHockey Championships 2015 - Lee Valley Hockey Centre, Queen Elizabeth Olympic Park - 26/8/15
Caia van Maasakker celebrates scoring the second goal for Holland with Carlien Dirkse van den Heuvel (R)
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Cricket - England v Australia - Investec Ashes Test Series Fifth Test - Kia Oval - 23/8/15
England's Alastair Cook talks with Mark Wood before the start of play
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Republican presidential candidate and Governor of Ohio John Kasich (R) fist bumps a young boy as he attends the Iowa State Fair in Des Moines, Iowa August 18, 2015. REUTERS/Joshua Lott 

Boxing - Frankie Gavin & Matthew Macklin Press Conference - The Old Library at The Custard Factory, Birmingham - 18/8/15
Jason Welborn and Matthew Macklin (R) pose after the press conference
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A young boy greets police officers in riot gear during a march in Baltimore, Maryland May 1, 2015 following the decision to charge six Baltimore police officers -- including one with murder -- in the death of Freddie Gray, a black man who was arrested and suffered a fatal neck injury while riding in a moving police van, the city's chief prosecutor said on Friday. REUTERS/Lucas Jackson 

U.S. President Barack Obama fist bumps the cashier after paying for his order at Franklin Barbecue in Austin, Texas July 10, 2014. REUTERS/Kevin Lamarque (UNITED STATES - Tags: POLITICS BUSINESS TPX IMAGES OF THE DAY) 

(L-R) Musicians Samuel Moore, Mavis Staples and Justin Timberlake fist bump after Moore sang during a Memphis Soul music workshop hosted by first lady Michelle Obama in the State Dining Room of the White House in Washington April 9, 2013. REUTERS/Larry Downing (UNITED STATES - Tags: ENTERTAINMENT) 

Canadian pop star Justin Bieber fist bumps with a girl from northeastern Japan, the area devestated by the March 11 earthquake and tsunami at an event at the U.S. Ambassador's residence in Tokyo May 18, 2011. In Japan for several concerts, the 17-year-old Canadian teen idol spoke briefly with nearly a dozen of children and exchanged messages. REUTERS/Yuriko Nakao (JAPAN - Tags: ENTERTAINMENT PROFILE DISASTER) 

U.S. first lady Michelle Obama (L) gives a fist bump to a journalism scholarship recipient at the White House Correspondents' Association Dinner in Washington May 9, 2009. REUTERS/Jonathan Ernst (UNITED STATES POLITICS) 

Mickey Rourke, best actor nominee for his role in the film "The Wrestler," does a fist bump with singer Seal at the 81st Academy Awards in Hollywood, California February 22, 2009. Mickey Rourke is dressed in Jean-Paul Gaultier. REUTERS/Jason Reed (UNITED STATES) (OSCARS-ARRIVALS) 

US Democratic presidential candidate Senator Barack Obama (D-IL) bumps fists with his wife Michelle (L) before his speech at his South Dakota and Montana presidential primary election night rally in St. Paul, Minnesota, June 3, 2008. REUTERS/Eric Miller (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA) BEST QUALITY AVAILABLE 

A man holds onto his mobile phone with his hand decked out in gold rings and chains during the funeral of former East End villian Lenny McClean August 5. Hundreds lined the streets in east London to pay their last respects to man who was reputed to have never been beaten in illegal bare knuckle fighting.

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