Roger Federer has reflected on his missed passing shot vs Jack Sock at the ATP World Tour Finals.
Federer was playing the American when a passing shot opportunity arose, which then led to Sock doing something rather unexpected.
He turned around and stuck his backside out towards Federer - not something you see everyday on a tennis court.
This clearly had an impression on the shot as Federer sunk the passing shot into the net.
Federer saw the funny side, though, stating that the initial target of the passing shot was smaller than the target Sock gave him.
This was a light moment in what was a very closely contested game, which saw Federer prevail in two close sets 6-4, 7-6.
Federer lost just four points behind his first serve as he came through an entertaining match without facing a break point.
Sock, 25, never looked like causing an upset after dropping his opening service game, but clung on impressively in the second set before the pressure eventually told.
Federer served out the opener after 36 minutes, but could not close it out in the second as five break points slipped by across the seventh, ninth, and 11th games.
"I got off to a great start, my big hope was I was going to be able to play a bit more freely after that," said Federer.
"The second set was tight, I missed some opportunities, the breaker could have gone either way and in the end he helped me with some double faults and some mistakes.
"I'm really happy that I got through somehow."
Watch the missed passing shot and Federer's reaction in the press conference in the videos below.
The 36-year-old is making his 15th appearance at the end of season event in London. He is looking for his seventh victory at the event after last winning the trophy in 2011.
Sock was making his debut at the tour ending event after reaching the required ranking to qualify, and he definitely made an impression with his antics on court.