In a strange match, Roger Federer played well for two sets before falling away in the third.
|Roger Federer sets up to serve to Juan Martin del Potro at the O2 arena in London|
Federer started the match very well, dominating proceedings in the first set before playing a horrible tiebreaker.
|Roger Federer hits a forehand winner against Juan Martin del Potro at the WTF in London|
Federer broke early in the second set, which then went with serve, Federer taking the set 6/4.
However, del Potro broke early in the decider for a 3-0 lead. Federer couldn't make any inroads on the Argentine's serve, and del Potro gave Roger plenty to think about heading in to the semi-finals tomorrow.
|Roger Federer pauses for thought during his defeat to Juan Martin del Potro at the WTF in London|
As it stands, del Potro will advance as group winner courtesy of his head-to-head result against Federer, meaning Roger will face Djokovic in the semis.
However, if David Ferrer manages to beat Tipsarevic later, there will be a 3-way tie at the top, and Federer will emerge as the group winner over del Potro, courtesy of sets won/lost difference. If that scenario unfolds, then Roger will face Murray in the semis tomorrow instead.
Who would you prefer Roger to play in the semis?