BASEL • In the last four editions of the Swiss ATP Indoors tournament, Stan Wawrinka was beaten in the first round.

So the reigning US Open champion was naturally apprehensive when he squared up against local wildcard Marco Chiudinelli in the first round of this year's tournament in Basel on Tuesday.

The world No. 3 nearly came unstuck, losing the first set 6-7 (1-7), before claiming the next two 6-1, 6-4 and the match in a struggle lasting 21/2 hours.

The three-time Grand Slam winner, who claimed the Flushing Meadows crown two months ago, needed five match points to reach the second round, clinching victory with a 16th ace in a match where he struck more than 35 unforced errors.

The Swiss, who has never progressed past the semi-finals in a dozen previous appearances, actually saved face for seeds on a day of first-round upsets.

Earlier, Lithuanian qualifier Richard Berankis stunned second seed Milos Raonic 3-6, 6-3, 6-3, while Luxembourg's Gilles Muller beat sixth seed Grigor Dimitrov 6-7 (9-11), 6-4, 6-4.

Wawrinka admitted he was relieved to sneak past Chiudinelli, an ATP journeyman ranked 119.

"It was a tough physical and mental battle," Wawrinka said. "It was a huge fight with Marco, he was playing at home and had the crowd on his side.

"It was so tough to beat him. He played great and I had to fight, I needed to work hard to find a winning solution.

"The third set was so tight, I'm just very content to get past the first round. I'll prepare for Thursday and hope to go further in the tournament."

AGENCE FRANCE-PRESSE