HOUSTON, Nov 15: World number one Andy Roddick is finding life tough at the top as he was forced to dig deep to sneak past feisty Argentine Guillermo Coria 6-3 6-7 6-3 on Friday to book the last semifinal berth at the ATP Masters Cup.

Despite his struggles, Roddick now finds himself in good position to add one more jewel to what has been glittering season as he closes in on a seventh title and a winner’s purse of $1.4 million.

Roddick’s win sets up an intriguing showdown with Roger Federer, the raw, brute power of the U.S. Open champion against the finesse and all-round game of the Swiss Wimbledon champion.

The other semi-final will also feature a grand slam winner, Australian Open champion Andre Agassi taking on the surprise package of the Masters Cup, Rainer Schuettler of Germany.

Since taking possession of the number one ranking in Paris last month, Roddick has quickly discovered that staying on top of the tennis summit may indeed be tougher than climb to get there.

Roddick’s first match as number one ended in a loss to Britain’s Tim Henman and while his three matches here have produced two wins, the 21-year-old American has been stretched to the limit, each time needing three gruelling sets to get the job done.

With second place in the Red Group and a place in the final four on the line, Roddick’s match with Coria may have been the toughest of them all.

With his thundering serve and punishing forehand finding their mark, Roddick claimed the only break of the opening set to open his account.

When he broke the Argentine again to forge 2-1 ahead in the second the American looked in full control.

But suddenly the match swung, the fourth-ranked Coria immediately breaking back, playing some inspired tennis to force the second set to a tiebreak which he took 7-4 when a faltering Roddick double faulted.

The slim Argentine carried the momentum into the third, breaking Roddick to open the set.

But just as suddenly as it appeared to be slipping away the match would swing back in Roddick’s favour, the American sweeping through the final five games and closing out the match with two booming aces.

Federer enters Saturday’s match with a confidence boosting 4-1 record over Roddick and as the only player not to lose a match closing out round-robin play earlier in the day with a 6-3 6-1 victory over Spain’s Juan Carlos Ferrero.

In the day’s only other match Carlos Moya beat Schuettler 7-5 6-4.

Moya’s victory was the only one in six matches played by the two Spanish players, the Masters Cup proving to be far from an ideal build-up for the pair as they head off to Melbourne for the Davis Cup final with Australia.

Results:

Red Group: 1-Andy Roddick (U.S.) beat 4-Guillermo Coria (Argentina) 6-3 6-7 (4-7) 6-3; 7-Carlos Moya (Spain) beat 6-Rainer Schuettler (Germany) 7-5, 6-4

Standings Player Matches won/lost Sets w/l Games w/l Rainer Schuettler (Germany) 2-1 4-4 43-42 Andy Roddick (U.S.) 2-1 5-4 51-42 Guillermo Coria (Argentina) 1-2 4-4 36-39 Carlos Moya (Spain) 1-2 3-4 29-36

Blue Group 3-Roger Federer (Switzerland) beat 2-Juan Carlos Ferrero (Spain) 6-3 6-1

Standings Player Matches won/lost Sets w/l Games w/l Roger Federer (Switzerland) 3-0 6-1 43-23 Andre Agassi (U.S.) 2-1 5-4 46-48 David Nalbandian (Argentina) 1-2 3-4 31-32 Juan Carlos Ferrero (Spain) 0-3 1-6 21-38

Saturday schedule 5-Andre Agassi (U.S.) v 6-Rainer Schuettler (Germany) 3-Roger Federer (Switzerland) v 1-Andy Roddick (U.S.)—Reuters