Roger Federer was subject to a 'videobomb' from Jack Sock whilst the Swiss was conducting an interview on Sky Sports with Mark Petchey.
The 36-year-old was analysing his serve in the second set of the encounter with Marin Cilic with the sky broadcaster, little did he know, however, that Sock was stood right behind him nodding ironically in agreement in his beanie hat at the pair's depiction of Federer's technique.
World No. 2 Federer quickly turned around and the pair laughed and joked at the American's intrusion upon the show.
The eight-time Wimbledon champion was understandably in high spirits after fighting back from a set down to beat Croatian world No. 5 Cilic 6-7 (5-7), 6-4, 6-1 on Thursday afternoon - thereby maintaining his 100% record at the 2017 ATP Finals.
Federer got his ATP Finals campaign underway with a straight-sets win against Sock the intruder last Sunday, the five-time Australian Open winner then dispatched German Alexander Zvevrev 7-6 (5-7), 6-1 on Tuesday before his clash with Croatian Cilic.
It's been somewhat of a renaissance 2017 for veteran Federer, who won his 25th Masters title at Indian Wells and a record-breaking ninth Gerry Weber Open finish to complement the two aforementioned Grand Slam victories.
American Jack Sock has also surged to prominence in the men's singles this year after spending most of his career in the doubles format of the game. The 25-year-old has gone from a ranking of 18 to nine within the space of one year, he was victorious at the Paris Masters and reached the semis of the BNP Paribas Open as well.
He's the first American to win at a masters event since Andy Roddick in 2010.
Federer and Sock are in the same group at the ATP Finals, and the American struggled to contend with Federer in the opening game, but has since recorded three-set triumphs over Cilic and Zvevrev.
The former doubles player Sock encounters Bulgarian Grigor Dimitrov in the group stage on centre court on Saturday evening - an opponent he defeated at the 2017 BNP Paribas Open.
Federer meanwhile has progressed to the last four of the competition having upheld his 100% group stage record.
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