Serena Williams retained the No. 1 world ranking by being the best player in her family last night.

Williams defeated older sister Venus, 6-4, 3-6, 6-3, in the semifinals of the Sony Ericsson Open at Key Biscayne, Fla. It was their 20th sibling showdown, and each has won 10 times.

Serena needed to reach the final to retain the top ranking she has held since Feb. 2. Otherwise she would have been supplanted next week by No. 2-ranked Dinara Safina.

Serena's opponent tomorrow will be 19-year-old Victoria Azarenka of Belarus, who beat Svetlana Kuznetsova, 6-3, 2-6, 7-5. Azarenka became sick to her stomach before losing a fourth-round match against Williams at the Australian Open in January.

Serena jumped to a 4-1 lead in the final set against Venus and broke serve for the sixth time in the final game. When she closed out her victory, she hopped in delight, raised a fist and shouted "Yes!" She then met her sister at the net with a handshake and slap on the back.

Top-ranked Rafael Nadal lost in the men's quarterfinals to 20-year-old Argentine Juan Martin del Potro, 6-4, 3-6, 7-6 (3). The upset delighted a partisan crowd.

"Wonderful for the crowd," Nadal said. "Terrible for me."

Del Potro had lost all nine sets in their four previous matches, but he was buoyed by a home-court advantage, with many fans singing "Del-Po" between points.

"They helped me a lot," del Potro said.

The No. 6-seeded del Potro's opponent today will be No. 4 Andy Murray, who beat No. 8 Fernando Verdasco, 6-1, 6-2.

BASEBALL

Minnesota Twins right-hander Scott Baker was placed on the 15-day disabled list yesterday with shoulder stiffness and will miss his scheduled opening day start.

Left-hander Francisco Liriano will instead take the mound for Minnesota on Monday against Seattle, but pitching coach Rick Anderson said the move — made retroactively to last Saturday, making Baker eligible to return April 12 — was precautionary and would only cause him to miss the first turn in the rotation.

Baker developed some soreness Wednesday after throwing in a minor league game, but he said he wasn't concerned.

"The decision technically wasn't up to me. I could definitely have pitched," said Baker, who signed a $15.25 million, four-year contract last month. "I'm an investment. They want to protect their investment."

GOLF

STRONG WIND SUSPENDS FIRST ROUND IN HOUSTON

The first round of the Shell Houston Open at Humble, Texas, was suspended because of high wind with only half the 144-player field on the course.

The round will resume this morning.

A morning thunderstorm postponed the start of the tournament by 2 1/2 hours. Play was then stopped because of wind that was strong enough to move balls on the slippery greens before players could mark them. The round was suspended for the day at 3 p.m. after wind gusts reached 50 mph.

Lee Westwood shot a 4-under 32 on the front nine to take a two-shot lead before the horns sounded across the course.

Castle High alum Dean Wilson, Punahou grad Parker McLachlin, and Nationwide Tour regular Keoke Cotner, a Kamehameha alum, did not tee off.

IN THE COURTS

SUIT COSTS MICHIGAN HIGH SCHOOL ASSOCIATION $6M

The Michigan High School Athletic Association has agreed to pay $6 million in legal fees to the winners of a gender-equity case that changed the seasons for girls' basketball and volleyball.

Lawyers representing a group called Communities for Equity would get $2.5 million, followed by smaller annual payments until May 2015, according to documents filed this week in federal court in Kalamazoo.

The agreement still needs the approval of U.S. Chief District Judge Paul Maloney.

The high school association and the group that successfully sued had asked that the deal be confidential, but Maloney refused.

SAILING

GOLDEN GATE PICKED FOR CUP CHALLENGE

American software billionaire Larry Ellison scored a significant victory yesterday in his quest to win the America's Cup when San Francisco's Golden Gate Yacht Club was declared the Challenger of Record.

The unanimous ruling by New York's top court gives Golden Gate, which backs Ellison's BMW Oracle Racing, the right to negotiate race terms with Societe Nautique de Geneve, the Swiss club that backs two-time defending champion Alinghi.

The next America's Cup had been scheduled for this summer but was delayed because of this protracted case that had entangled yachting's showpiece event. It is still unclear when competition will actually begin.

AND WHAT'S MORE ...

England's Ross McGowan tied his lowest European Tour score, shooting a 7-under 64 to take a two-stroke lead over Northern Ireland's Michael Hoey after the opening round of the Estoril Open at Cascais, Portugal.