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The 23-year-old Argentine, playing hs first clay-court event since last year's French Open, won 6-2 7-5.

On a rain-hit day, French Open champion Gaston Gaudio beat Christophe Rochus 7-6 (7-3) 6-2 and Juan Carlos Ferrero eased past Ivo Karlovic 6-4 6-1.

Spain's Rafael Nadal beat fellow teenager Gael Monfils 6-3 6-2.

Coria dominated last year's clay-court season, winning 31 straight matches before losing to Gaudio at Roland Garros.

His year was then interrupted by shoulder surgery and, apart from a Davis Cup tie last month, has not played on his favourite surface since Paris.

"I feel that I'm on the right track again, but I have to build my confidence," said Coria.

Roland Garros was a major disappointment and it was very difficult for me Guillermo Coria

"I'm not at the level I was last year yet, but I've improved my physical strength and put on three kilos.

"What I need now is wins under my belt."

Coria was the dominant player on clay last year, going on a 31-match winning streak before losing to Gaudio with a spectacular collapse at Roland Garros.

"Roland Garros was a major disappointment and it was very difficult for me," said Coria.

"But it's made me more determined. I'm determined to become an all-surface player, not just a clay court specialist.

"But one thing I know is that because of what happened to me last year at Roland Garros, if I ever do win the French Open, it will be even sweeter than if I had won it last year."

In other matches, seventh seed Joachim Johansson fell to Felix Mantilla, 2-6 6-3 6-2.

And Frenchman Cyril Saulnier ended the challenge of Thailand's Paradorn Srichaphan with a 6-2 6-4 victory.

Rain delays Henman bid

Play was abandoned for the day with Tim Henman trailing Mariano Zabaleta by a set.

Flags are flying at half mast at this week's venue, the Monte Carlo Country Club, following the death of Prince Rainier.