DALLAS — Dirk Nowitzki started to grab the part of his left leg that hurt the most, then stopped. He might not have known what to rub first.

So the reigning league MVP dejectedly put a hand on his head. Then pounded the court.

Nowitzki was injured on an ugly looking fall in the third quarter of Dallas' 88-81 loss to the San Antonio Spurs on Sunday, but left the arena without knowing how bad it is. The team termed it a "lower left leg injury" and said more details would come Monday.

"I fell awkwardly and my left leg got caught underneath of me," Nowitzki said in a statement. "I am going to get re-evaluated in the morning and I hope to have more information then."

Nowitzki went down after running and jumping to block a shot late in the third quarter. With Nowitzki writhing on the court, Tim Duncan grabbed the loose ball and scored, putting San Antonio ahead for the first time in the second half. It came during a 19-0 run that took the Spurs from 12 points down to in control the rest of the way.

San Antonio won its third straight since a 1-6 slump and got some breathing room over Dallas in the Western Conference playoff race. The Spurs also won the season series 3-1, which would help should the teams wind up tied — but the Mavericks may have to worry about just making the playoffs if Nowitzki's injury is as severe as it looked.

Dallas hasn't beaten a winning team since Jason Kidd arrived. The Mavs are 0-8, including their last three, all at home. They were 29-4 at home — without losing as many as two in a row — before falling to the Lakers, Celtics and now the Spurs.

All three games were close at the end. Dallas lost the last two despite holding Boston to 34.5 percent shooting and San Antonio to 33 percent.

"We have to keep our composure," said Kidd, who had seven points, seven rebounds, five assists and three turnovers. "We put ourselves in position to win, but we didn't finish it off. The margin of error is real small. We were right there but couldn't hit a shot."

With 12 games left, the Mavericks are 44-26. They're ahead of Golden State for the final playoff spot, but the team they may have to watch most is Denver, which is on the outside looking in. The Nuggets were 41-28 going into a game at Toronto on Sunday afternoon.

Dallas next plays the Clippers at home on Tuesday, then plays at Denver on Thursday and at Golden State on Sunday.

"Hopefully they'll come into practice tomorrow with a renewed sense of optimism knowing that the season is not over," Mavs coach Avery Johnson said.

Manu Ginobili led San Antonio with 26 points. He started the game-breaking rally with a layup and a 3-pointer, then hit a 3 to cap it. He also was 11-of-11 from the foul line. Dallas took only 11 free throws all game.

"When we were losing, we were flat. We had no emotion," Ginobili said. "We needed a game like this. It's good to see us react like this."

Duncan finished with 19 points and 13 rebounds, despite missing 11 of his first 12 shots. He made six of his last nine.

"I liked the shots I took," Duncan said. "I felt I got fouled on a couple of them, but that's neither here nor there. I knew I had to be patient, to wait to see if the worm turned and finally did."

Things didn't turn right for Tony Parker, who was 4-of-21. He scored 13 points.

"Our defense won the game," Parker said. "When you shoot like that, you need defense to give yourselves a chance to win."

Jerry Stackhouse led Dallas with 19 points and was automatically ejected with 13.9 seconds after getting his second technical of the game; the other came for using Ginobili's face to help get up after the two collided going for a rebound late in the third quarter.

"It's not a big deal," Ginobili said. "We were both competing."

Said Stackhouse: "Nothing new with him."

Jason Terry scored 17 points, Josh Howard 13 and Nowitzki had 11. He also had three blocks and was part of the reason Duncan got off to such a rough start.