LONDON - The Williams sisters pulled out of women's doubles at Wimbledon on Tuesday, with Serena saying it's because she wants to focus on her bid for a fourth consecutive Grand Slam title in singles.

The official reason for the withdrawal was given as Serena's "soreness."

Both siblings won first-round singles matches in straight sets Monday.

"Following yesterday's match, I feel it would be best for me to concentrate on singles here at Wimbledon, and as a result, have made the decision to withdraw from doubles," Serena said in a statement. "I've always loved playing doubles with Venus, particularly here at Wimbledon where we've had so much success over the years, and so I'm really sorry to have to withdraw this year."

She trailed 3-1 at the start and later slipped and tumbled to the turf during the first set of Monday's 6-4, 6-1 victory over Margarita Gasparyan. Venus, who is older than Serena, beat Madison Brengle 6-0, 6-0.

Serena has won 22 Grand Slam matches in a row and seeking to complete another self-styled "Serena Slam" with a fourth straight major title. She also has a chance at the first calendar-year Grand Slam since Steffi Graf did it in 1988.

The two siblings have teamed to win 13 Grand Slam doubles titles as a pair, most recently at Wimbledon in 2012.

They have not even been as far as the semifinals at a major tournament in doubles since losing in that round at the 2013 U.S. Open.

The sisters have yet to play a doubles match together this season. Their most recent competition was last year's U.S. Open, when they lost in the quarterfinals.

When the Williams sisters played doubles at the All England Club last year, they stopped after three games in the second round, after Serena served four consecutive double-faults. She had looked disoriented during warmups, having trouble grabbing tennis balls tossed to her by ball kids. The reason given that day was that Serena was ill.

Misaki Doi of Japan and Stephanie Vogt of Liechtenstein replaced the Williams sisters in this year's draw.

The Slovakian team of Dominika Cibulkova and Anna Karolina Schmiedlova also pulled out of the doubles at Wimbledon on Tuesday.

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