Roger Federer has struck back in his 2012 French Open quarterfinal match versus Juan Martin del Potro. Down two sets, he easily took the third, 6-2. Federer cleaned up his game quite a bit -- after suffering 28 unforced errors in the first two sets, he committed just five in the third. Meanwhile, del Potro struggled to get his first serve in and was broken twice.
Through four sets and change, Federer has actually won more overall points than del Potro (96 to 94), but his errors-- and a sporadic serve -- cost him dearly at the start of the match and in the second-set tiebreaker.
You can see a full French Open scoreboard at SI.com.