ROME " Fourth-ranked Andy Murray lost for only the fourth time this year, upset by Argentine qualifier Juan Monaco 1-6, 6-3, 7-5 on Wednesday in his opener at the Rome Masters.
Murray easily won the first set before missing several first serves and committing unforced errors, while the 58th-ranked Monaco won several points with an effective drop shot.
"To be fair, he started playing a lot better," Murray said. "It wasn't my best match, but I was still very close to winning."
Murray's other losses this year came against top-ranked Rafael Nadal " twice in Masters Series events in Indian Wells, Calif., and at Monte Carlo " and to Fernando Verdasco at the Australian Open.
Monaco will next face 15th-seeded Marin Cilic after the 6-foot-6 Croatian beat Christophe Rochus of Belgium 6-0, 5-7, 6-2.
Nadal and Roger Federer both advanced in straight sets. Nadal took the crowd out of play with a methodical 6-2, 6-3 win over Andreas Seppi, the top-ranked Italian at No. 37, while Federer beat big-serving Ivo Karlovic 6-4, 6-4.
In another upset, Jurgen Melzer of Austria eliminated seventh-seeded Nikolay Davydenko 7-5, 7-6 (5). Davydenko missed two months earlier this season with a left heel injury, but he reached the quarterfinals in Monte Carlo and the semifinals in Barcelona the last two weeks.
Also, eighth-seeded Verdasco eliminated the last American in the draw, Mardy Fish, 6-4, 5-7, 6-3; No. 12 Fernando Gonzalez beat Janko Tipsarevic 6-4, 6-4; Paul-Henri Mathieu of France eliminated 11th-seeded David Ferrer 6-3, 2-6, 6-2; and Robin Soderling of Sweden overcame a second-set lapse to beat Romanian qualifier Victor Crivoi 6-1, 6-7 (2), 6-1.
In the first round, held over from Tuesday due to rain, Richard Gasquet beat ninth-seeded Jo-Wilfried Tsonga 7-6 (2), 6-4. Tommy Robredo of Spain also eliminated Philipp Kohlschreiber of Germany 6-2, 7-6 (5) and will now play defending champion Novak Djokovic.
Gasquet then beat Ernests Gulbis of Latvia, 6-2, 1-6, 6-4, in his second match of the day, while Mathieu lost to Mischa Zverev of Germany, 3-6, 7-6 (5), 6-0.
Also advancing was fifth-seeded Juan Martin Del Potro, who dispatched Viktor Troicki of Serbia, 6-3, 1-6, 6-3.
Seppi beat Nadal on a hard court in Rotterdam last year, and he had the fans cheering when he broke the Spaniard in the opening game. But the top-ranked Nadal broke right back and eventually extended his winning streak on clay to 26 matches.
Nadal won this clay-court warmup for the French Open three consecutive times from 2005-07 and he is trying to become the first player in the Open era to win it four times.
The 6-foot-10 Karlovic had 15 aces to Federer's one, but he couldn't hold serve.
"I got off to a good start in both sets, which is always good, kind of comforting against Ivo," Federer said. "He found his groove later on with his serve, but I already had the break in the second, which is perfect."
With the sun out at the Foro Italico after two days of rain, something in the air got into Monaco's eye and he had to call the trainer and receive eye drops midway through the first set.
Monaco fell to the clay trying to react to a passing shot from Murray, but he got back up, wiped the dirt off his side and proceeded to beat Murray and improve to 13-6 on clay this year, including a runner-up result in Buenos Aires, Argentina, in February.
Murray made his first clay-court semifinal appearance in his last outing in Monte Carlo, but he showed he still has some work to do before the French Open, which begins May 24. He's been working with two-time French Open finalist Alex Corretja during the clay-court season.
Murray could still move up to No. 3 in the rankings if Djokovic does not defend his title.
"I haven't been playing my best on clay and that's something I'm going to have to work out," Murray said. "But I've had a great eight months. I haven't lost early in a long time and I knew it was going to happen sometime. I've just got to move on and work hard for Madrid."