In the days leading up to the Western Conference finals, experts at NBA think tanks tried to analyze how the Oklahoma City Thunder would operate without injured 6-foot-10 forward Serge Ibaka.

If Game 1 were any indication, the answer is: not very well. With the league's No. 2-ranked shot-blocker missing because of a strained left calf, the San Antonio Spurs had relatively unimpeded passage to the basket and defeated the Thunder 122-105.

The series will resume in San Antonio on Wednesday -- without Ibaka, who probably is gone for the remainder of the playoffs.

"I thought they were able to get anything they wanted," Thunder coach Scott Brooks said. "We have to do a much better job defensively."

San Antonio outscored the Thunder 66-32 in the paint. Spurs forward Boris Diaw said scoring inside was emphasized by his team with Ibaka not around. Spurs guard Tony Parker added, "Obviously, it makes a huge difference with Ibaka not there."

Forward Tim Duncan led the Spurs with 27 points. Reserve guard Manu Ginobili scored all 18 of his points in the second half. Forward Kawhi Leonard and guard Danny Green scored 16 apiece, with Green converting four of five 3-point shots.

Parker, playing on a tender left hamstring, was more of a facilitator than scorer, producing 14 points and 12 assists. Parker said distributing instead of trying to score was not an effort to compensate for the injury.

"That's what they were giving us," Parker said. "They double-teamed me, came hard on the pick-and-rolls, and Timmy was open."

Forward Kevin Durant scored a game-high 28 points for Oklahoma City, and guard Russell Westbrook added 25 points.

The Spurs shot 57.5 percent from the floor for the game, far better than the Thunder's 46.3 percent success rate.

Oklahoma City erased an eight-point halftime deficit and led by one twice during the third quarter. Westbrook was most responsible for the comeback, shifting into an attacking gear to score 12 points in the period.

The Spurs, meanwhile, threw up some clumsy shots, but they regrouped with a 10-0 push and finished the quarter ahead by seven.

Brooks attributed the brief recovery to a defense that was temporarily diligent.

"They got two easy looks off of mistakes, but other than that, I didn't think they got anything easy in that third quarter," Brooks said.

San Antonio dominated much of the first half but came away with just a 67-59 lead. The Spurs once led 63-48.

Duncan scored 21 first-half points, hitting nine of 12 shots. Parker added 12 points and six assists before the break, and Leonard scored 11. Green gave San Antonio a quick boost with eight points in a span of 1:13 of the second quarter. He made a pair of 3-pointers.

San Antonio shot 62 percent in the half and outscored Oklahoma City 40-18 in the paint, where the Thunder missed Ibaka as a deterrent at the rim.

Durant scored an efficient 16 in the half, converting five of seven shots, including both of his 3-point attempts. Durant received some much-needed supplemental help from reserve guards Derek Fisher and Reggie Jackson, who scored 11 and nine points, respectively. Fisher, the long-time Spurs nemesis, hit three of four 3-pointers in the half.

Fisher wound up with 16 points, and Jackson scored 13.

Westbrook took over for a chunk of a third quarter, but Oklahoma City could not maintain the effort. In the end, the Thunder did not summon nearly enough defense to challenge the Spurs for 48 minutes, a deficiency they will have to overcome without Ibaka.

"We play team defense," Durant said. "We don't just rely on Serge. He's a big part of what we do. He's injured for the rest of the postseason, so we've got to move past that and keep playing as a team."

NOTES: Spurs F Boris Diaw was poked in the lower right eyelid late in the first quarter by Oklahoma City C Steven Adams. Diaw left the game and returned later in the second quarter with a swollen eye but no structural damage. ... F/C Nick Collison, who replaced injured F/C Serge Ibaka (calf) in Oklahoma City's starting lineup, had not started a game all season before Monday. He finished with no points and three rebounds in 16 minutes. ... Oklahoma City, 4-0 against San Antonio during the regular season, won one game without G Russell Westbrook, one that Spurs F Kawhi Leonard missed, and a third when Spurs G Manu Ginobili didn't play. Leonard also missed the second half of the game in which Westbrook didn't play. ...The Spurs are in their ninth conference finals since F/C Tim Duncan joined the team in 1997-98, more than any other NBA team during that span.