HOUSTON -- Andy Roddick was being outplayed, outhustled and, yes, even outserved. Then, suddenly, he summoned the skills and grit that made him No. 1.

Down a break in the final set and reeling a bit, Roddick went on a 10-point run to wrest control and pulled away to beat Guillermo Coria 6-3, 6-7 (4), 6-3 Friday night, qualifying for the Tennis Masters Cup semifinals.

"I can't remember a match where I've been down in the dumps and turned it around so quickly and been back in the locker room 20 or 30 minutes later with a win,'' said Roddick, 21, the second-youngest player to end a year atop the ATP Tour rankings.

"My confidence just soared up from nowhere.''

He went 2-1 in round-robin action and advanced to a semifinal Saturday (ESPN2, 11 p.m. ET) against Wimbledon champion Roger Federer (3-0). Coria (1-2) was eliminated.

The other semifinal Saturday (ESPN2, 3:30 p.m. ET) will pit No. 5 Andre Agassi against the man he beat in the Australian Open final, No. 6 Rainer Schuettler. Already assured of advancing, Schuettler lost his last round-robin match 7-5, 6-4 Friday to Carlos Moya.

The fourth-ranked Coria played nearly flawless tennis in the second set and the early part of the third, which he led 3-1. But Roddick won the final five games of the match with some spectacular play -- and with some help from his Argentine opponent.

Coria was up 3-2, 40-love when he missed five consecutive forehands to get broken.

"I didn't keep my concentration there,'' Coria said. "I relaxed a little too much, and I started to get nervous after the second forehand I missed.''

Roddick won the next five points, too, including holding at love for a 4-3 edge with the help of a 136 mph service winner.

His serve working much better than it did in the middle portion of the match, Roddick cruised at the end, closing the match with back-to-back aces.

"It was a match that changed a lot,'' Coria said. "I had a chance and I couldn't take advantage. He got a lot of confidence and strength, and he was unstoppable.''

He had won the prematch coin toss and chose to let Roddick serve first, as if to say, "Bring it on!''

Coria did return very well for stretches, and Roddick's serve wasn't its best: Among other problems, he double-faulted to hand over the second-set tiebreaker. During the changeover, Roddick chopped his racket into his bag a half-dozen times.

That tiebreaker featured the point of the tournament, a lengthy exchange culminating in this sequence: Coria stretched to hit a defensive lob; Roddick chased it down and, with his back to the net, smacked a shot through his legs; Coria lofted another lob; Roddick pounded an overhead; Coria got to it and delivered a passing shot that Roddick volleyed into the net.

Roddick finished with 12 aces and a total of 38 winners -- 13 more than Coria -- in a riveting match. Roddick even was moved to applaud a couple of Coria's better efforts.

It was a matchup of contrasting styles: Roddick's power against Coria's quickness and touch. Yet both displayed plenty of the other's chief traits.

Roddick showed deftness at the net, repeatedly winning points with feathery drop volleys, and he often came out on top of lengthy baseline rallies by expertly changing pace. Coria, for his part, had just as many forehand winners as Roddick, nine, and was very effective with his serve, holding at love three times in the middle set and saving one break point with an ace.

Now Roddick will take on Federer, who owns a 4-1 career edge, including a straight-set victory in the Wimbledon semifinals this year. The American did win their most recent match, though, at the Canada Masters in August.

Federer overwhelmed French Open champion Juan Carlos Ferrero 6-3, 6-1 Friday to give himself a chance of finishing the season ranked No. 2.

"I'm just happy the season is ending nicely,'' said Federer, who also beat Agassi and David Nalbandian this week. "I was in a tough group, so to come through so easily -- the last two matches especially -- is surprising.''

Federer is tied with Roddick for the tour lead with six tournament victories in 2003, and the Swiss star's 76 match wins are the most this season.

"I came here with one goal, and that was to finish No. 1,'' Roddick said. "Now that I've done that, everything's a bit of a bonus.''

His midmatch woes against Coria might have been a result of fatigue. It's the final week of a grueling season, and Roddick puts forth as much effort as anyone.

"I'm not going to fake you out. I'm pretty taxed, mentally and physically, from the year,'' the U.S. Open champion said, "but the finish line is in sight.''