Sure feels good, for those of us Fed fans, to have him through to the semis without major stress! In his match today against David Ferrer, Roger Federer certainly wasn't playing his A game. It's always a big plus, when looking at the stats, to find the winners higher than the errors, and today that certainly wasn't the case. However, it also has to be taken into consideration when playing an opponent the quality of David Ferrer, who is one of the best returners in the game, that hitting winners is much more challenging when the shots just keep coming back. Even with first serve percentages, it can affect a person when they know their serve is going to be returned unless it is something special, as Roger himself noted after the match. But no one said a win has to be pretty - a win is a win - and in this case, because it was in straight sets, it ensures a semifinal berth.
At this point Federer is the only one in either group with a definite place in the semis. Even Djokovic, though he has won both his previous two matches, did so with the loss of a set; therefore there is room, if he were to lose in straight sets tomorrow, to still not make it in, though a pretty unlikely scenario. Murray and Berdych are in similar situations as each other, with each having won and lost the same amount of matches and sets, though Berdych will have a little bigger challenge on his hands trying to beat the #1 player in the world. It all gets quite complicated and I'm not going to try to give all the particulars which I don't understand myself. But I think the only one who doesn't have any chance to qualify for the semis would be Tipsarevic, who lost both his matches so far in straight sets.
Lots more good tennis to still come in the next four days, watching only the best of the best.