"We could have been sharper down the stretch," Spurs guard Antonio Daniels added. "In the fourth quarter, we had some key turnovers and missed shots, which is going to happen."
Game 2 of the best-of-seven series is Tuesday at Los Angeles.
Duncan had 26 points, 21 rebounds, five assists and four blocks, all team highs. But he missed his first 10 shots and finished 9-of-30 from the field. San Antonio shot just 32 percent (28-of-88).
"Shots weren't falling for me," Duncan said. "I just tried to continue to be aggressive and take the shots that were there and they just weren't going down for me. I just kind of fell into a hole there."
"He had a lot of great shots," Popovich said. "They didn't go down and we would have been in better shape if they did, but you can say that about anybody who doesn't have a great night shooting."
Despite Duncan's troubles and the continued absence of injured 7-footer David Robinson -- who usually defends the massive O'Neal -- the Spurs still held a 67-63 lead after a banker by Duncan with 9:53 left.
But the MVP candidate took a seat, and the impact of his absence was immediate. O'Neal hit a lane jumper, got loose for a fast-break dunk and sank two free throws to give LA the lead.
"We were right there," Duncan said. "We held them where we wanted them. We had a chance. We just couldn't turn that corner."
Duncan was 0-of-10 in the first quarter. But O'Neal was struggling with his wrist injury and Bryant picked up two fouls, allowing San Antonio to take a 17-13 lead.
After finally making a bank shot early in the second quarter, Duncan got untracked and scored 10 points in the period. He made three straight baskets to widen the lead to 38-29 before Brian Shaw answered with a 3-pointer before halftime.
O'Neal banged his hand on the rim with 8:45 left in the third quarter and the Lakers trailing, 40-37. They rallied for a 48-46 lead without him but trailed, 61-57, entering the final period.
"We've been through every situation imaginable in basketball," O'Neal said. "We know what it takes to win games. It was one of those days for us, however, we still mustered up enough energy to win the game."
Former Spur Samaki Walker had 12 points and nine rebounds for the Lakers, who held a 54-48 edge on the glass.
Smith scored 16 points, Tony Parker added 11 and Malik Rose 10 and eight boards for the Spurs. Rose often guarded O'Neal after starting center Mark Bryant quickly got into foul trouble
