Flushing Meadows, NY (Sports Network) - World No. 1 Victoria Azarenka held off defending champion Samantha Stosur on Tuesday to secure a berth in the semifinals at the U.S. Open.

The Australian Open champion Azarenka edged out the seventh-seeded Stosur 6-1, 4-6, 7-6 (7-5) at Arthur Ashe Stadium, where rain delayed play for 75 minutes with the Belarusian leading 3-0 in the first set. With the victory, Azarenka is guaranteed to remain atop the women's rankings next week.

Azarenka steamrolled her way though the first set before Stosur fought back in the second.

In the third set, Azarenka went out to a 4-2 lead following a break, but Stosur got the break back and eventually forced the match-deciding tiebreak.

Azarenka set up her first match point in the tiebreak with a backhand drop- shot winner, and converted on it when Stosur sent one final backhand beyond the baseline after 2 hours, 23 minutes of quality tennis.

The Minsk native Azarenka is now a perfect 11-0 in three-set matches this year and a flawless 7-0 lifetime overall versus Stosur, having won 14-of-15 sets.

The 23-year-old Azarenka will now appear in her fourth career Grand Slam semifinal and her first one at the U.S. Open.

Stosur stunned American great Serena Williams in straight sets in last year's U.S. Open finale and was a French Open runner-up in 2010.

Azarenka will meet the Maria Sharapova-Marion Bartoli winner on Thursday. Azarenka beat the French Open champ Sharapova in the Aussie Open final back in January.

The women's quarterfinals will conclude Wednesday on the hardcourts at the National Tennis Center, where the fourth-seeded Wimbledon champion and Olympic gold medalist Williams will encounter 12th-seeded fellow former world No. 1 Ana Ivanovic of Serbia and 10th-seeded French Open runner-up Sara Errani will battle 20th-seeded fellow Italian and doubles partner Roberta Vinci.

Williams owns 14 major singles titles, including three at the U.S. Open, where she's also a two-time runner-up.

The Sports Network