MASON, Ohio — Venus Williams’ reinvigorating week ended with a bad back and gritty comeback that wasn’t quite enough.

Williams played through back pain that forced her to get treatment and reduced her second serve to 63 mph by the third set. China’s Li Na took advantage, reaching the final of the Western & Southern Open with a 7-5, 3-6, 6-1 victory Saturday night.

All week long, Williams showed she’s learned how to cope with an immune system disease that causes tiredness and sore joints. She made it through three grueling, three-set matches to get to the semis, and was ready for another one.

The bad back was too much. By the end, she was just trying to get her serve over the net. She considered quitting, but decided to keep playing.

“I pretty much couldn’t serve,” she said. “But I wanted to try, especially since this is my first semifinal of the year. I wanted to try to see if I could get to the final. It didn’t work out for me.”

Li is trying for her first title this season. She lost in finals at Sydney, Rome and Montreal, where Petra Kvitova beat her for the Rogers Cup title a week ago.

Kvitova played Angelique Kerber in the other semifinal Saturday night. Kerber ended Serena Williams’ 19-match winning streak a day earlier.

Serena watched from a seat in the stands next to the players’ tunnel while her older sister wore down. At one point in the final set, she yelled: “Break her!” Venus smiled, knowing she was in no shape to do it.


∫ Men: At Mason, Ohio, no medal involved this time. Little drama, either. Novak Djokovic simply ground his way to another title shot. And Roger Federer will be waiting for him.

Djokovic reached the finals of the Western & Southern Open for the second straight year Saturday, beating Juan Martin del Potro 6-3, 6-2 in a reprise of their meeting in the Olympics. Del Potro defeated Djokovic for the bronze medal on Wimbledon’s lush grass two weeks ago.

The sequel on a hard court? Not even close. The final will match the world’s top two players, the first time that’s happened in Cincinnati. If Federer wins, it’ll give him a record five titles in the tournament.

“It’s a nice bonus, really,” Federer said. “When I was a kid I wasn’t thinking of winning five Cincinnatis, but then again here I am in this great situation being able to do it, the first man ever. So I’m obviously excited.”

Top-ranked Federer beat Swiss countryman Stanislas Wawrinka 7-6 (4), 6-3 in the other semi. It’ll be the seventh time that Federer and Djokovic have played for a tournament title.

 the last time in 2011 at Dubai. Federer beat Djokovic for the Cincinnati title in 2009.

Federer leads the career series 15-12, but it’s taken a few interesting turns lately. Djokovic beat him in the semifinals at the U.S. Open last year, then again in the semis at Rome and the French Open. Federer got the upper hand again in the semifinals at Wimbledon.

“I hope I’m fresher than him tomorrow,” Federer said. “We’ll see how it goes.”

Djokovic also reached the Cincinnati final last year but had to quit in the second set because of a sore shoulder, giving the title to Andy Murray.