At 4-2 in the fifth set, Mardy Fish suddenly found much-needed spark after a pretty lethargic afternoon of lost opportunities. Having broken Arnaud Clement’s serve, Fish emphatically took control of a match he’d carelessly allowed Clement to extend.

Fish cracked three of his 15 aces, including one at 134 mph, to put away Clement, a challenger he hadn’t been able to shake. Clement, a tour veteran from France playing his 51st Grand Slam - the most of any active player - had succeeded not only in coming back from a 2-sets-to-1 deficit, but in drawing Fish into long rallies that neutralized the American’s attacking game.

Fish outlasted Clement in 3 hours, 33 minutes, 4-6, 6-3, 6-4, 1-6, 6-3.

For much of the match, Fish played passively, seemingly content to engage in protracted, claycourt-like exchanges with the Frenchman. Clement, a former Top 10 player who at age 32 is now down to 68 in the world, set the scene by making Fish work hard on his serve in the very first game, breaking the American after a nine-minute exchange of deuce and ad points.

Fish, who’s famously thin and on a winning streak this summer, reaching four of six finals, looked somewhat enervated. His serve didn’t have the sting nor his groundstrokes the pop that he exhibited on his run during the US Open series. Fish’s forehands were caressed rather than cracked, and at one point in the fourth set he hit a first serve at a lethargic 82 mph.

Although Fish was missing his killer instinct, he’d didn’t lack for opportunities. After losing the first set, he took the next two. Few in the capacity crowd of pro-Fish fans - who offered the hoary if quaint chant, “Do you have any aces? Go Fish!” - expected the match to go to five.

But in the fourth set, Fish went away, even whiffing on a service return, and lost it 6-1, giving the Frenchman, who had advanced to this matchup when his previous opponent retired with an ankle injury, new hope.

With the crowd imploring him on, Fish snatched a 3-1 lead in the final set with an aggressive volley punched down the line, the break of serve that would provide the necessary margin.

With Andy Roddick and golden boy Ryan Harrison gone, Fish now leads a second-tier trio of Americans, including John Isner and Sam Querrey, hoping to make it into the second week of the Open. Fish plays the victor of the match between fellow American James Blake and Novak Djokovic, the No. 3 seed.

Match Facts

- Advancing to the fourth round, this is Fish’s best performance at a Grand Slam this year.

- Fish finished third in the US Open series behind Andy Murray and Roger Federer.

- Fish has shot up in the rankings, from 108 in March to no. 21 at the beginning of the Open.