By Sarah Holt
BBC Sport at Wimbledon
Andy Roddick battled past Sebastien Grosjean to claim his place in the last four with a 3-6 6-2 6-1 3-6 6-3 win.
After a brief rain delay, Grosjean took advantage of a sluggish Roddick, breaking at 4-2 to race to the opener.
Roddick rediscovered his serve and forehand in the second set to break the Frenchman twice, before racing to the third set in just 31 minutes.
Another lapse saw Grosjean steal the fourth but Roddick picked up the pace, making the decisive break in the fifth.
Roddick will now face 12th seed Thomas Johansson in Friday's semi-final.
The American looked out of sorts in the first set, making unnecessary advances to the net which Grosjean pounced on to take his first set from Roddick since 2002.
But last year's runner-up immediately switched tactics in the second, changing his serve direction and dictating the match with his stinging groundstrokes.
Roddick's quick-thinking paid off as he raced to the second, carrying the momentum into the third as Grosjean's game crumbled.
But the Frenchman was given a lifeline when Roddick's concentration slipped in the fourth, allowing Grosjean to break at 4-2.
The American had chances to break straight back but Grosjean clung on to force the decider.
Roddick came out strongly, breaking the ninth seed to take a 3-0 lead and, despite some resistance from Grosjean, the American 22-year-old advanced to the semi-finals for the third straight year.
"I came here losing a string of five-setters at Grand Slams so to pull something out against Sebastien means a lot," Roddick told BBC Sport.
"He was coming up with the goods and I let it slip in the fourth - he normally makes you pay for that but I hung in there.
"Wimbledon is definitely one of my favourite places to play so it means a lot to me to reach the semi-finals.
"Now more than ever I needed a result like this and I would like to go a step or two now."
Grosjean, who practices with Roddick, admitted the American's powerful serve ultimately made all the difference out on Centre Court.
"He was serving really well and agressively in the fifth," said the French ninth seed.
"Each time I stayed with him at the beginning of the set I went on to win it but when I gave him the opportunity to get ahead he took it.
"Now if Andy is serving well and feeling confident he can beat anyone."