Sam Stosur, Sloane Stephens among 1st-round losers on Day 1 at Wimbledon

Belgium's Yanina Wickmayer serves to Australia's Samantha Stosur during their first round match at the All England Lawn Tennis Championships in Wimbledon, London, Monday, June 23, 2014. (AP Photo/Sang Tan) (The Associated Press)

Maria Kirilenko of Russia plays a return to Sloane Stephens of U.S. during their first round match at the All England Lawn Tennis Championships in Wimbledon, London, MondayJune 23, 2014. (AP Photo/Pavel Golovkin) (The Associated Press)

Former U.S. Open champion Sam Stosur and 18th-seeded American Sloane Stephens were among the early losers Monday on the opening day of Wimbledon.

Stosur, the 17th-seeded Australian, fell in straight sets 6-3, 6-4 to Belgium's Yanina Wickmeyer.

The loss extended the 2011 U.S. Open winner's poor run at Wimbledon, where she has never advanced past the third round and has lost in the first round six times in 12 appearances.

Wickmeyer was watched by retired star Kim Clijsters, who has been working with the fellow Belgian player.

Stephens, meanwhile, had her streak of reaching the second week at six consecutive Grand Slam tournaments ended with a 6-2, 7-6 (6) loss to 109th-ranked Maria Kirilenko of Russia.

Stephens saved five match points serving at 5-6, but Kirilenko closed out the match in the tiebreaker after a wide forehand by the American.