SAN ANTONIO (AP) -- The San Antonio Spurs were not going to believe Serge Ibaka was really injured until the Oklahoma City Thunder took the court in the opener of the Western Conference finals without their athletic big man.
Their skepticism was unwarranted.
Ibaka is indeed injured and Oklahoma City needs to find a way to replace his defensive presence against San Antonio.
Tim Duncan had 27 points and the Spurs took advantage of Ibaka's absence to score more than half their points in the paint, beating the Thunder 122-105 Monday night in the opener of the best-of-seven series.
Tony Parker did not appear limited by a hamstring injury, adding 14 points and 12 assists in 36 minutes in San Antonio's first victory over Oklahoma City this season.
Parker and coach Gregg Popovich both said earlier they weren't sure if the Thunder would actually be without Ibaka, who injured his left calf in Oklahoma City's series clincher against the Los Angeles Clippers.
"Contrary to what San Antonio was thinking, he's not coming back," Thunder coach Scott Brooks said.
That's bad news for Oklahoma City entering Game 2 on Wednesday.
San Antonio had 66 points in the paint and shot 58 percent from the field. It was the highest shooting percentage allowed by the Thunder in the postseason since relocating from Seattle.
The Thunder got their usual offensive output from All-Stars Kevin Durant and Russell Westbrook, who scored 28 and 25 points, respectively. But Oklahoma City's remaining starters, Nick Collison, Thabo Sefolosha and Kendrick Perkins, combined to score five points with 13 rebounds and one assist.
Collison started in place of Ibaka and was 0 for 3 from the field with three rebounds and one blocked shot.
Ibaka was averaging 12.2 points, 7.3 rebounds and 2.23 blocks in 33.9 minutes in the postseason.
"We play team defense, we don't just rely on Serge," Durant said. "He does a great job of blocking shots, but it's all because of our team defense. He's a big part of what we do. He's a starter, had his best season this year, so of course we're going to miss his presence, but we have guys that are going to step up and do it collectively."
San Antonio planned to attack Oklahoma City's interior whether Ibaka was playing or not, and found it much easier to do without the athletic 6-foot-10 forward.
"We always want to try to penetrate," Parker said. "We always want our ball movement, that's how we play -- kick and pitch and stuff like that. You know, obviously it's a little bit better with (Ibaka) not being in the paint, but we're still going to try to penetrate and make stuff happen."
The Spurs fed Duncan early and the veteran responded by scoring 12 points on 6-of-7 shooting in the opening quarter.
Parker, who sustained a Grade 1 left hamstring strain in San Antonio's series clincher against Portland, drove the paint and dished to Duncan early before looking for his own shot midway through the quarter.
"That's part of our game plan," Duncan said. "He knew that they weren't going to let him shoot the ball like he did in the last series. They were going to try to take that away from him, so he knew he was going to have to be an assist man."
Parker scored all but two of his points in the first half.
Manu Ginobili took over in the second half, scoring all 18 of his points with a series of breakneck drives and 3-for-4 shooting on 3-pointers.
"Just got to do a better job of closing the paint off," Westbrook said. "I thought we did a better job in the second half of just putting more pressure on them, making it tough for them to get inside the paint."
After starting Collison and bringing in 7-foot post Steven Adams to spell him and Perkins, Oklahoma City continually altered its lineup in an attempt to derail San Antonio's attack. At one point the Thunder had Westbrook and fellow point guards Reggie Jackson and Derek Fisher on the court with Durant playing the post defensively. Duncan responded by dropping in a running hook on Durant.
"We're going to have to find lineups that work," Brooks said. "I have faith in all of our guys to step in and do the job, no matter who we put on the floor."
With the exception of a pair of free throws by Fisher, Westbrook and Durant scored all of Oklahoma City's points in a 23-22 third quarter.
The Thunder rallied to take a 76-75 lead on Westbrook's 17-foot jumper with 5 minutes left in the third quarter for their first lead since the opening basket of the game.
"I think we need more from everybody defensively," Brooks said. "We scored 105 points. ... We scored enough points to win a basketball game. We have to do a better job defensively."
San Antonio improved to 7-1 at home in the playoffs, winning its past five games by an average of 20.6 points.
The Spurs, however, remember what happened in the 2012 conference finals, when the Thunder won four straight to rally from an 0-2 deficit.
"They're a talented team," Ginobili said. "They're going to watch video; they're going to fix mistakes. It's going to be harder for sure. It's just one down."
NOTES: Durant was assessed a technical foul 30 seconds into the fourth quarter after throwing his fists down in frustration after being assessed a foul. . Boris Diaw was poked in his lower right eyelid early in the game, but returned to shortly thereafter once it was determined there was no structural damage. . Play had to be stopped twice to clean up blood on Collison, who was battling Duncan and Splitter defensively.
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