The Celtics ended a 17-year drought in San Antonio -- fittingly on St. Patrick's Day.

Pierce led Boston with 30 points as the Celtics beat the Spurs 91-85 on Saturday night. The Celtics last beat the Spurs in San Antonio on Feb. 14, 1990. The Spurs had won 18 straight against the Celtics and 15 straight at home.

"It feels good," Pierce said. "Regardless of who was supposed to be the favorite coming in. Especially the way it went down -- us having the big lead and them coming back and then us keeping our composure."

Delonte West had 23 points, Al Jefferson added 20 points and 12 rebounds and Rajon Rondo grabbed 14 rebounds.

After trailing the entire game, the Spurs rallied in the fourth to twice take the lead.

"We had one quarter tonight where we really locked it down and did a good job defending," said Tim Duncan. "But other than that we gave up too many (shots) percentage-wise and too many points in the paint."

Tony Parker led the Spurs with 30 points. Duncan added 20 points and 16 rebounds and Michael Finley had 10 points. They shot just 37 percent from the field.

The Spurs were down 75-62 at the beginning of the final quarter and had been behind by 19.

But, as they've made a habit of doing when down at home, the Spurs turned it on to start the fourth.

"We played terrible for three quarters," said Manu Ginobili. "We made a great effort down the stretch to come back. We were even ahead but then they made a couple of great shots and we stopped. Down the stretch we couldn't get anything done so that means a lot in games like this."

They went on a 15-4 run, highlighted by Finley's dunk and key 3-pointer, that brought them within two points with 6:31 left. Parker made two foul shots 59 seconds later to tie at 81, then passed on the next possession to Duncan, who went well above the rim to jam it for an 83-81 lead.

Pierce tied it again, then Duncan matched him for a Spurs lead.

"You go on the road to play San Antonio and you tell me it's a two-point game with two minutes left, I'll take that," Pierce said.

After Pierce tied it at 85, Bruce Bowen committed a turnover leading to Gerald Green's dunk with 1:05 remaining.

Parker was called for traveling and Pierce converted for a jumper with 16.9 seconds left for an 89-85 lead. West then made two foul shots with 6.5 seconds left to clinch the win for Boston.

"We tried to make a comeback but it's tough to do that," Parker said.

The Spurs were coming off a 101-90 loss in Milwaukee on Thursday that snapped their season-high 13-game winning streak.

The Celtics, who have the league's second-worst record, lost Friday to the Dallas Mavericks 106-101.

"It was a game of momentum. We had it going then all of a sudden in the fourth, we couldn't really do anything," Michael Olowokandi said. "Coach just told us to be solid on the defensive end. That's what we did and it worked out."

When the teams met in Boston in January, the Spurs nearly blew the game in the fourth when the Celtics used a late 13-0 run to make it close. The Spurs held on for a 93-89 victory, after having led by 23 in the third quarter.

The Celtics had last beaten the Spurs on Jan. 8, 1997, the season before Duncan entered the NBA.

"It was nice to get the monkey off the back with the Tim Duncan thing," Boston coach Doc Rivers said.

"It's more like a gorilla, definitely," Pierce said.

Boston got off to a fast start Saturday, holding the Spurs to 15 points and taking a 14-point lead into the second.

Boston kept a double-digit lead throughout the second until Duncan stole the ball from Kendrick Perkins and was able to get it to Brent Barry, who threw the long pass to an all-alone Parker for the fast-break layup with 6:19 left. Parker's score brought the Spurs within nine.

The Spurs used Boston's foul trouble and poor shooting from the field (28 percent in the period) to get within 45-40 at the half.

Boston opened the second half with a 10-0 run until Parker's score more than 3 1/2 minutes in.