In Friday’s semifinals, Williams will play 2011 French Open champion Li Na of China.

Asked in an on-court interview if her game is peaking, Williams replied: “No. Not yet. I hope not. I’m just trying to do the best that I can.”

Through five matches, Williams has dropped a total of 13 games so far. For comparison’s sake: Suarez Navarro lost more games than that in her previous match alone, 15, while eliminating No. 8 Angelique Kerber.

“The conditions were so tough, so it definitely was not her best tennis today,” Williams said of the windy conditions and Suarez Navarro, who was playing in her third career major quarterfinal Tuesday, which happened to be her 25th birthday.

Williams ended with a 20-3 edge in winners. She made fewer unforced errors, 12-9 and won 23 of 26 points on first serves.

When Williams did face a break point for the first time, 42 minutes and 11 games into the match, she came up with a big serve and raced forward for a simple putaway that she punctuated with a yell. Moments later came a second break chance, but even with Williams stumbling to the court, Suarez Navarro dumped the ball into the net.

In men’s fourth-round action in the afternoon, top-seeded Novak Djokovic won 45 of 53 service points while eliminating 43rd-ranked Marcel Granollers 6-3, 6-0, 6-0 in a grand total of only 79 minutes.

Djokovic, who won the 2011 US Open and lost last year’s final to Andy Murray, reached his 18th consecutive major quarterfinal. Next up is a match against 21st-seeded Mikhail Youzhny of Russia, who was two points from defeat but came back to edge two-time major champion Lleyton Hewitt 6-3, 3-6, 6-7 (3), 6-4, 7-5.

The other men’s matches were at night, with Murray facing Denis Istomin of Uzbekistan, and No. 5 Tomas Berdych playing No. 9 Stanislas Wawrinka.

Earlier Tuesday, the fifth-seeded Li needed nearly 21/2 hours to get past 24th-seeded Ekaterina Makarova of Russia 6-4, 6-7 (5), 6-2.

On three occasions, Li went up a break in the second set, nearing eventual victory each time, but could not finish things. She then was up 3-0 in the tiebreaker before faltering. Still, she recovered well and closed the match by taking the last four games, then joked that she would grab a bag of chips and enjoy watching Williams against Suarez Navarro.

Regardless of who she’d face next, Li made the point that what would be important is to focus on herself.

“I mean, if you only think about what [your] opponent [is] doing, of course you already lose the match before you come to the court,” Li said. “For tennis you have to figure out what you have to do on the court, what you should do.”

Li has only won one of nine career matches against Williams heading into Friday.

“Tough, tough opponent,” Li said. “But is [a] good challenge to play against her.”

The quarterfinals on the other half of the draw are Wednesday: second-seeded Victoria Azarenka of Belarus against 48th-ranked Daniela Hantuchova of Slovakia, and 10th-seeded Roberta Vinci against 83rd-ranked Flavia Pennetta in a matchup between two Italians in their 30s.

While the other women in that section all advanced Monday, Azarenka’s fourth-round match against 2008 French Open champion Ana Ivanovic was postponed until Tuesday at 11 a.m. because of rain. Azarenka got off to a slow start, but eventually got going and beat the 13th-seeded Ivanovic 4-6, 6-3, 6-4 in a topsy-turvy match with a combined 16 service breaks and 17 double-faults.

“I think,” two-time Australian Open champion Azarenka said, “we’re just great returners.”

Lamented Ivanovic: “I felt like I could break her, but it was very frustrating that I was losing my serve constantly.”