Roger Federer opened up the ATP World Tour Finals with a win over Jack Sock at the 02 Arena.
The Swiss won 6-4, 7-6 (4) against the lowest ranked player in the competition and made light work of his opponent.
Federer is chasing his seventh ATP Finals title after clinching his 50th win of the year against Sock on Sunday.
With both Andy Murray and Novak Djokovic injured, Federer and rival Rafael Nadal are the main attractions on the court this week.
Nadal, who will end the year ranked number one in the world, faces David Goffin on Monday. He will be hoping for a win similar to what Federer managed himself.
Although the 36-year-old looked on fine form while dispatching Sock, there was one hilarious moment that appeared to distract him on Sunday.
His American opponent played a rather lazy drop shot, which Federer should have had no problem smashing back to take the point.
But as he ran up to return the ball, Sock turned around and bent forward at the net, showing his backside to Federer.
The view was clearly enough to distract the current Wimbledon and Australian Open title holder as he slammed the ball into the net, losing the point.
Check out the moment below.
And after the match, Federer commented on that moment.
"It was a big distraction because it was very big. That's what I should have aimed for," he joked.
"That target was bigger than the down-the-line court that I had!"
It's good to see Federer is enjoying the competition and not taking things too seriously.
However, had the point been more important and if he ended up losing the match, his reaction would probably have been very different.