.U.S.Open .wins also for Murray, Juan Martin Del Potro and Kim Clijsters
NEW YORK, (Reuters) – Serena Williams moved closer to her third grand slam title of the year by knocking out Spain’s Maria Jose Martinez Sanchez in straight sets Friday to reach the fourth round of the U.S. Open tennis.

“She was serving really well, and I think especially in the second set,” Williams said after the 6-3 7-5 victory on a warm and near-cloudless day at Arthur Ashe Stadium.

“I just kept fighting, and every time I had a break point I felt like I had a chance to win one of them. I thought she served well. I couldn’t get down about it.”

On the men’s side, second seed Andy Murray of Briton beat Paul Capdeville of Chile 6-2 3-6 6-0 6-2 to reach the third round and Argentine Juan Martin Del Potro bounced Austrian Juergen Melzer 7-6 6-3 6-3 in his second-round match.

In other showcase matches, Belgian Kim Clijsters continued her comeback against compatriot Kirsten Flipkens, while under the lights, two-times champion Venus Williams was to face Slovak Magdalena Rybarikova before number three seed Rafael Nadal takes the court against Nicolas Kiefer of Germany.

Serena was down a break in the second set but recovered to win the one-hour, 27-minute match against her net-rushing opponent.

The Australian and Wimbledon winner screamed and pumped her fist repeatedly in the 56-minute final set, inspiring both herself and the 23,000 sun-baked spectators.

“I got super pumped in the second set when I got down 1-3,” said the defending champion, who will next play 22nd seed Daniela Hantuchova of Slovakia.

“I felt I needed to do something to charge my battery, so to say, and I just wanted to play harder and do better.”

World number 43 Martinez Sanchez, who had 18 winners and 18 unforced errors, was broken for the final time in the 11th game before Williams served out the match at love.

Sixth seed Del Potro, who next plays Austrian Daniel Koellerer, had never gone beyond the third round of a slam until he reached the quarters at Flushing Meadows a year ago.

The 6-foot-6 (1.98 m) right-hander with six career titles used that as a springboard to reach the quarters at the Australian Open and the semis at Roland Garros this year.

Del Potro enjoys the New York atmosphere but is not talking up his chances of being the last man standing a week from Sunday.

“This is my favorite grand slam,” said Del Potro, who beat Andy Roddick in the Washington finals last month. “I love to play here. I have a good respect for this tournament.

“I want to be quiet with my matches, with my game, and then we will see.”