Roger Federer has seen a lot during his many years on the tennis circuit.

But we’re guessing that he’s never been distracted by an opponent’s bum during a match.

[RELATED: Roger Federer beats Jack Sock to clinch opening win in London]

However, that’s exactly what happened against Jack Sock during their clash at the ATP World Tour Finals, with the American spinning round, bending over and – incredibly – pushing Federer into an unlikely error.

See Sock’s novel tactic below:

Not that it produced any long-term reward. Sock still lost the match 6-4 7-6, but kudos to him for trying something different!