No. 2 seed and 2007 ATP titles leader Rafael Nadal retired with a left arm injury in his opening round match against Argentine Juan Monaco, trailing 6-7(5), 1-4.

Nadal, a winner of six titles this season, received treatment after dropping the opening set. After losing his serve in the fifth game of the second set, he then retired.

After both players exchanged breaks in the first set, Nadal jumped off to a 4-2 lead in the tie-break before Monaco won five of the next six points to win the set. Nadal was broken in the first game of the second set and then again in the fifth game.

It was Monaco's third Top 10 win of the season and of his career (first on hard courts) and he will take on American wild card Sam Querrey, who rallied to defeat No. 13 seed Mikhail Youzhny 5-7, 6-3, 6-4.

The 19-year-old Californian fired 17 aces and broke in the seventh game of the final set to post his second Top 10 victory of his career. Youzhny moved into the Top 10 this week for the first time after reaching the third round in Montreal.

Unseeded Juan Carlos Ferrero, who reached the final last year, upset No. 6 seed Fernando Gonzalez 6-2, 7-6(7), to reach the third round in Cincinnati Wednesday.

The 27-year-old Spaniard converted three of 10 break points and only lost his serve once in the one hour and 29 minute match. He had lost three of the four previous meetings, including twice on hard courts.

In the opening set, Ferrero broke in the fourth and eighth games. In the second set, Gonzalez broke in the opening game and led 2-0 before losing serve in the fourth game. In the tie-break, Gonzalez led 3-1 before Ferrero rallied back, winning on his third match point.

He will face the winner of Nicolas Kiefer and No. 9 seed James Blake.

Former No. 1 Lleyton Hewitt, the 2002 and '04 runner-up, led No. 8 Richard Gasquet 6-1, 3-2, before the Frenchman retired with a blister on his right hand after 51 minutes of play.

Hewitt will face Austrian Jurgen Melzer, who saved two match points in his 6-3, 2-6, 7-6(9) victory over Mario Ancic. The

Spaniard Nicolas Almagro defeated No. 11 seed Ivan Ljubicic 6-4, 6-4, winning back-to-back matches on hard courts for the first time this season. Almagro converted two of two break points and was never broken in the 65 minute match. He will take on Jarkko Nieminen, who upset No. 7 Tommy Robredo, in the third round.

No. 16 seed David Ferrer, a quarterfinalist last year, reached the third round with a 6-2, 7-5 victory over in-form Radek Stepanek. The 25-year-old Spaniard converted four of 10 break points and only lost his serve once against Stepanek, who won his second career ATP title in Los Angeles and reached the semifinals at ATP Masters Series Montreal last week.

Ferrer, one of three Spaniards to win Wednesday, will take on No. 3 seed and defending champion Andy Roddick in the third round on Thursday. Roddick has won two of their previous three meetings.

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