Venus Williams can’t get past Li Na and an aching back

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 at Mason, Ohio, 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.”

On the men’s side in Ohio, Novak Djokovic and Roger Federer won their semifinal matches to set up a Sunday showdown.

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.

Federer beat Swiss countryman Stanislas Wawrinka, 7-6 (4), 6-3, in the other semifinal. 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.

ETC.

Ibaka, Thunder agree to deal

The Oklahoma City Thunder took a big step toward sticking around as an NBA championship contender, locking up forward Serge Ibaka with a contract extension.

Ibaka posted on Twitter that he was happy for the chance to play for the Thunder for five more years. The team didn’t provide details of the deal, but Yahoo Sports first reported that the deal is for four additional years and $48 million.

Thunder General Manager Sam Presti dismissed the notion that Ibaka’s signing means that guard James Harden’s departure is inevitable. But with more than $50 million committed per season to All-Stars Kevin Durant and Russell Westbrook and starting center Kendrick Perkins, there is not much room left in the budget for Harden, who earned a spot on the U.S. Olympic team that won gold in London.

Jacques Villeneuve was in the driver’s seat heading to the white flag, more than 20 car lengths ahead and his first victory in NASCAR just a lap away on the Montreal track named for his dad.

Then, in the blink of an eye, Justin Allgaier bumped past him for the victory Saturday in a Nationwide race as a stunned crowd at Circuit Gilles Villeneuve recoiled in disbelief.

Having maintained the top spot through restart after restart in the final laps of a race that went six extra circuits around the 14-turn, 2.7-mile layout, Villeneuve was running low on fuel and kept turning off the engine of his No. 22 Dodge to conserve.

What seemed like an insurmountable lead vanished on the last lap. Allgaier closed in a hurry as Villeneuve suddenly slowed and Allgaier hit him from behind.

Villeneuve, who started third, overcame three late restarts in a wild race that saw Danica Patrick lead 20 laps.

Sam Hornish Jr.finished second and Villeneuve was third, giving Dodge two in the top three. Elliott Sadler and Ron Fellows rounded out the top five.

Patrick, who also ran second to Villeneuve for 12 laps, suffered a broken rear axle after her Chevy hit a shoe fan’s thrown on the track as she was tracking Villeneuve in her rearview mirror. She finished 27th.

Nelson Piquet Jr.’s lead was so big that even low on fuel he could cruise carefully to the finish line for a long-awaited victory in the NASCAR Trucks Series at Brooklyn, Mich. Jason White finished second and Dakoda Armstrong was third.

Even-money favorite Lady of Shamrock, strengthening her claim as America’s best 3-year-old filly competing on grass, rallied from last-place under Hall of Fame jockey Mike Smith to score a narrow but convincing win in the featured Grade I $300,000 Del Mar Oaks.

Allowed to trail her eight rivals until the far turn, the John Sadler-trained filly surged into contention on the far outside entering the stretch and outfinished the surprising 43-1 longshot Stormy Lucy in winning by a half-length.

Open Water, another outsider at 25-1, was third, 2½ lengths behind Stormy Lucy.