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American Sam Querrey (pictured), who captured his maiden ATP title in Las Vegas (d. Anderson) earlier this month and finished a semifinalist in Delray Beach (l. to Nishikori) in February, hit eight aces and saved all three break point opportunities he faces in beating World No. 81 Carlos Berlocq of Argentina 7-6(4), 6-3 in 82 minutes at the Sony Ericsson Open on Wednesday.

"I could have played a little better," said 20-year-old Querrey. "But for the first round it's nice to get by that, and hopefully I'll play a little better than that in my next one against [No. 10 seed Tomas] Berdych on Friday.

Croatian teenager Marin Cilic won 74 percent of first serve points against Kristof Vliegen of Belgium in a 6-3, 6-2 victory. The 19-year-old Chennai semifinalist (l. to Youzhny) goes on to meet World No. 16 Paul-Henri Mathieu of France in the second round.

Argentine 19-year-old Juan Martin del Potro, playing his first tournament since reaching the Australian Open second round in January, beat American wild card and World No. 162 Jesse Levine 7-5, 6-1 in 77 minutes to advance to the second round against Feliciano Lopez, the Spanish No. 32 seed who reached the Dubai final (l. to Roddick) earlier this month.

"I really didn't feel like he overpowered me with his serve," said Levine. "I felt like I was making a lot of returns, especially in the first set. And the second set, obviously, once he got his confidence going and he was up a break, he really could crack his serve a little bit harder."

Benjamin Becker became the first qualifier into the second round after the German beat Sergio Roitman of Argentina 6-3, 6-4 in 74 minutes. The World No. 108 will now challenge second-seeded Spaniard Rafael Nadal, who is hunting his first ATP title since Stuttgart in July 2007.

American supporters had reason to cheer when qualifier Sam Warburg, currently No. 157 in the South African Airways ATP Rankings, recorded his first ATP-level win since the Australian Open in January. Warburg defeated World No. 37 Potito Starace of Italy 7-6(2), 6-2 in 76 minutes to set up a clash with Argentine No. 15 seed and 2007 runner-up Guillermo Canas.

Nicolas Mahut, the Frenchman who advanced to the Pacific Life Open third round at Indian Wells (l. to Federer), struck 10 aces and converted four of six break point opportunities to knock out Florian Mayer of Germany 7-6(6), 6-3. The 26-year-old will next meet this season’s Costa do Sauipe finalist and No. 20 seed Carlos Moya of Spain, who reached the 2003 final (l. to Agassi).

Albert Montanes knocked out Japanese wild card Kei Nishikori (pictured) 7-5, 6-2 in 90 minutes to set up a meeting with Spanish compatriot and No. 22 seed Juan Carlos Ferrero, who has won all three of their previous career matches. Nishikori captured his maiden career ATP title at Delray Beach, Florida, in February, and is currently a career-high No. 120 in the South African Airways ATP Rankings.

Fabrice Santoro, 35, defeated 36-year-old Jonas Bjorkman 6-1, 6-0, in 48 minutes in a match-up between the two oldest players in the draw, and qualifiers Kevin Anderson of South Africa and Pablo Cuevas of Uruguay advanced to the second round.

Anderson fired 19 aces en route to a 7-6(4), 3-6, 7-6(5) victory over Agustin Calleri and Cuevas beat former Miami semifinalist Vincent Spadea 6-4, 6-2.

In the final match of the day, Nicolas Kiefer rallied to defeat lucky loser Guillermo Garcia-Lopez 4-6, 7-6(9), 6-4 in two hours and 21 minutes. The Spaniard was taking the place of German Tommy Haas, who withdrew due to a sinus infection, which he suffered in Indian Wells.

Kiefer saved two match points in the second set tie-break after Garcia-Lopez served for the match at 5-4.