Photos from Flushing Meadows: Semifinals

Serena’s 33, and she can kick.

​Each day during the U.S. Open, we'll feature Anita Aguilar's photography, captioned by Steve Tignor. For more photo galleries, click here.

Caroline Wozniacki has reemerged as a top-level player over the last two weeks.

Ponytail safely away from her racquet, Wozniacki beat Peng Shuai to reach her second U.S. Open final.

Peng hung tough early and used her backhand well.

But near the end of the second set, she began to suffer visibly.

Cramps and heat illness forced her from the court.

Wozniacki was concerned enough to come across the net and lend a helping hand.

She was eventually taken off the court on a wheelchair...

...As the crowd stood in concern.

Wozniacki said she felt for Peng after she was forced to retire.

As the sun went down, Serena Williams got down to business.

She was on her game from the start.

It was enough to make her opponent, Ekaterina Makarova, look a little ill herself.

The only thing not in Serena’s control was her hair.

Serena’s 33, and she can kick.

Serena won 6-1, 6-3...

...but it obviously meant a lot to her.

She says she would trade her five titles in 2014 for one major.

Later on Friday, a recovered Peng came to meet the media. She had trouble remembering much of the episode on court.

Nothing came easily for Novak Djokovic on Saturday.

He said he “just wasn’t myself” in his loss to Kei Nishikori.

Later, Djokovic’s coach, Boris Becker, said his man was, “Mentally a little bit tired,” after an eventful summer.

Nishikori, on the other hand, said “everything was working well.”

With Djokovic in white Uniqlo, Nishikori donned red in the scorching heat.

But he reached full flight after switching to white.

The win was the biggest of the 24-year-old’s career.

The Japanese fans in the crowd, and those watching at home at 4:00 in the morning, were pleased to see one of their own become the first Asian man to make a major final.

The last Asian-American man to reach a U.S. Open final, Michael Chang, is Nishikori’s coach. “He’s tough,” Kei said, “but I sometimes I need something, a push.”

After that, came The Cilic. Marin’s serve, under the tutelage of Goran Ivansevic, has become one of the biggest weapons in tennis.

It was far too much for Roger Federer, who was sent packing in an hour and 45 minutes.

Michael Jordan and Ahmad Rashad were the only two who could manage a smile in the Federer box.

Cilic said he played his “absolute best” from “first point to last.”

I hope Roger didn’t see Mirka in this pose.

Federer and the crowd tried in vain to find some hope.

But it didn’t last long.

Federer said he knew it would be a harder comeback than the one he made against Gael Monfils, based on the way Cilic was playing and serving.

By the third set, even MJ knew his man was in trouble.

Federer said he was happy there are no more Slams this year, so “the grass can grow over this one.”

Cilic finished in style, with three unreturnable serves and a backhand winner in the final game.

The Japanese sun rose over Ashe Stadium.

“That’s not a Grand Slam-winning kit, Roger” seemed to be the consensus on Twitter. The consensus was right.

Federer said there wasn’t a lot he could do, and that he was happy for Cilic. He’ll look forward to a Davis Cup semifinal on home soil this weekend.