MASON, Ohio (AP) — Roger Federer, Novak Djokovic and Simona Halep made quick work of their rain-delayed matches Friday afternoon and advanced to the quarterfinals of the Western & Southern Open, facing the daunting challenge of playing a few hours later in extremely humid conditions.

Several days of rain turned the quarterfinals into an endurance test. Six men’s and three women’s singles matches were held over from Thursday because of rain.

Federer — the top player left in the men’s bracket after No. 1 Rafael Nadal withdrew to get some rest — needed only 72 minutes to beat Leonardo Mayer 6-1, 7-6 (6), leaving him on course for yet another Cincinnati title. He’s won a record seven despite missing the tournament the last two years because of injury.

Then, it was off for a little rest before an evening match against fellow Swiss player Stan Wawrinka, who advanced with a 6-4, 6-4 win over Marton Fucsovics.

“Waiting around all day and hardly seeing any tennis obviously is never fun for the tournament and the fans,” Federer said. “So we’re happy that the tournament is back underway. Today I tried to really focus on just the one match, not thinking that there is possibly going to be two.”

Djokovic’s match against Grigor Dimitrov was suspended at the start of the third set on Thursday night. He finished off the defending champion 2-6, 6-4, 6-4, maintaining his hopes of a first Cincinnati title.

Dimitrov didn’t drop a set last year while winning his first Masters title in Cincinnati. He also won his first two matches this week in straight sets, a streak that was broken by Djokovic on Thursday night before the rains came and the match was suspended with Djokovic up 2-1.

“I wish it didn’t rain, for sure, last night,” Dimitrov said. “I just thought that even though I lost that second set, I was feeling well on the court.

“Today is a completely different day. The conditions are a little bit different. So yeah, everything came into play.”

With each win, Djokovic gets closer to the chance he covets — another appearance in the title match. He’s never won at Cincinnati, going 0-5 in title matches. It’s the only ATP Masters 1000 event that has eluded him.

Djokovic acknowledges he would especially enjoy winning the title, which would make him the only player to win all nine ATP Masters events.

Also Friday, Juan Martin del Potro and Nick Kyrgios split two tiebreakers before Del Potro prevailed in the third set for a 7-6 (4), 6-7 (6), 6-2 win. Del Potro will face David Goffin, who upset Kevin Anderson 6-2, 6-4 to reach the Cincinnati quarterfinals for the first time in three tries.

On the women’s side, No. 1 Simona Halep beat Ashleigh Barty 7-5, 6-4 to reach the quarterfinals. Halep has faced the most challenges from the rain, with one match suspended overnight Wednesday in the third set and then her third-round match held over for a day as well.

Barty, who lost to Halep in last week’s Rogers Cup semifinals in Montreal, committed 32 unforced errors to Halep’s 17. Halep is seeking her first Cincinnati championship after losing in the finals last year and 2015.