Roddick, Sharapova march on in Memphis

Memphis: Defending champion Andy Roddick was pushed for the second straight day before prevailing over Lu Yen-hsun 7-6, 6-4 on Thursday during the second round of the Memphis Championships.

After a tough three-set victory over fellow American James Blake in the opening round, Roddick relied on his serve to turn back Taiwa's Lu, who saved seven break points but faltered in the second set at 4-4.

"As well as I did some things tonight, if I want to move through this tournament I've got to do better on break points," Roddick told reporters.

"I've very close to playing really well and it's just a matter of tighten up a couple things."

Roddick, bidding for his third Memphis title, did not drop his serve as he clubbed 10 aces. He next faces fellow American Sam Querrey, who defeated Argentina's Leonardo Mayer 6-4, 6-0.

In the women's draw, top seed Maria Sharapova of Russia despatched eighth seed Elena Baltacha of Britain 6-2, 7-5.

Command performance

It was another commanding performance from Sharapova, who has yet to drop a set in Memphis, as she claimed a nip-and-tuck second set by breaking her opponent at 5-5. Sharapova will play fifth seed Petra Kvitova of the Czech Republic for a place in the final.

Second seed American Melanie Oudin failed to join Sharapova in the last four, losing to unranked Swede Sofia Arvidsson 6-1, 6-3.

"She wasn't missing anything," Oudin said of her opponent. "She played a really good match and there wasn't much I could do."

Arvidsson will play unranked Briton Anne Keothavong in the other semi-final.

Memphis International Women's singles quartersfinals (prefix denotes seeding):1-Maria Sharapova (Russia) beat 8-Elena Baltacha (Britain) 6-2 7-5; 5-Petra Kvitova (Czech Republic) beat 3-Kaia Kanepi (Estonia) 1-6 6-3 7-6(0); Sofia Arvidsson (Sweden) beat 2-Melanie Oudin (U.S.) 6-1 6-3; Anne Keothavong (Britain) beat Karolina Sprem (Croatia) 6-4 6-3

Men's singles second round (prefix denotes seeding): 1-Andy Roddick (U.S.) beat Lu Yen-Hsun (Taiwan) 7-6(2) 6-4; 8-Sam Querrey (U.S.) beat Leonardo Mayer (Argentina) 6-4 6-0; Ivo Karlovic (Croatia) beat Xavier Malisse (Belgium) 6-4 6-4; Lukas Lacko (Slovakia) beat Jeremy Chardy (France) 7-6(4) 2-1 (Chardy retired); 5-Tomas Berdych (Czech Republic) beat Michael Russell (U.S.) 3-6 6-3 6-2.

Buenos Aires Open

Men's singles, second round: 4-Juan Monaco (Argentina) beat Juan Ignacio Chela (Argentina) 7-6(3) 4-6 6-2 *8-Horacio Zeballos (Argentina) beat Carlos Moya (Spain) 6-4 6-4; 1-David Ferrer (Spain) beat Frederico Gil (Portugal) 6-3 6-0; 6-Igor Andreev (Russia) beat Marcel Granollers (Spain) 3-6 6-3 6-4