Serena, Li reach U.S. Open semis

World No. 1 and defending champion Serena Williams put forth an utterly dominating performance to reach the semifinals of the U.S. Open, while Chinese star Li Na also advanced to the final four of the season's final major during Tuesday's session.

Williams faced no resistance from No. 18 seed Carla Suarez Navarro in her quest for a fifth career U.S. Open title and second straight, with the 16-time Grand Slam winner needing a mere 52 minutes to double-bagel the overmatched Spaniard 6-0, 6-0 at the USTA Billie Jean King National Tennis Center.

The American star won an astounding 88 percent of her first serve points and ripped off 20 winners to claim a berth in the semis, where Williams will face Li after the fellow 31-year-old outlasted 24th-seeded Ekaterina Makarova by a 6-4, 6-7 (5-7), 6-2 count earlier in the day.

"I played really good. I was just more focused than anything," Williams said humbly.

Second-seeded Victoria Azarenka, who lost to Williams in last year's outstanding final in Flushing, was a hard-fought fourth-round winner on Tuesday. The Belarusian stalwart overcame 13th-seeded fellow former world No. 1 Ana Ivanovic 4-6, 6-3, 6-4 in just over two hours in a match that was postponed because of rain on Monday.

Ivanovic staved off two match points and broke Azarenka to pull within 4-5 in the final set.

In the next game, Azarenka broke right back after blowing a third match point before converting on a fourth when her Serbian counterpart netted one final two-handed backhand.

"I was, like, sleeping," Azarenka said. "I really had to wake up in the second set and try to fight for points.

"The match points were pretty bad. I really didn't go for my shots. I kept waiting for a mistake, and obviously it didn't happen."

Azarenka is now 5-2 lifetime against the 25-year-old 2008 French Open champion Ivanovic, including a victory in California last month.

The 24-year-old Azarenka, who is now 29-1 on hardcourts this year, will meet 30-year-old former top-10 star Daniela Hantuchova in a quarterfinal on Wednesday. The Slovakian Hantuchova edged out American fellow non-seed Alison Riske in three sets on Monday.

Azarenka and Hantuchova have split four career meetings, but the Belarusian has won the last two, including a win at Indian Wells earlier this season.

Azarenka is the two-time reigning Australian Open champion and lost to Serena Williams in last year's U.S. Open finale.

Meanwhile, the fifth-seeded Li fought off a stern challenge from the Russian Makarova in a match that lasted 2 hours and 20 minutes. The Chinese slugger recorded two of her seven service breaks in the third set, while Makarova failed to break Li in the deciding stanza of their quarterfinal.

Li is the first-ever Chinese player to reach the final four at the U.S. Open.

The 31-year-old Li was this year's Aussie Open runner-up to Azarenka and captured the French Open and was an Aussie Open runner-up in 2011. She'll now appear in her fifth career Grand Slam semifinal (3-1).

The 2013 U.S. Open champ will earn $2.6 million. The current world No. 1 Williams would claim an additional $1 million as a result of capturing the U.S. Open Series.