Boston, MA (Sports Network) - Caron Butler scored 21 points, and had seven points in the final minute to help Washington beat Boston, 88-83, and hand the Celtics their first losing streak of the season.

Antawn Jamison finished with 20 points and 10 rebounds for Washington, which also swept a home-and-home with Boston. The Wizards won by an 85-78 decision on Saturday. DeShawn Stevenson chipped in with 16 points for Washington, which has won three in a row.

Kevin Garnett had 23 points and nine rebounds for Boston, which came into the game with just five losses on the season. After each of their losses before Saturday, the Celtics followed with at least one win, and twice had nine-game winning streaks.

Paul Pierce had 18 points, and Ray Allen scored 16 for Boston, which has lost three of four.

"It's big for us," Jamison said. "You know, we've been doing a little bit of soul searching here lately, trying to figure out what type of team we want to be...We knew this was a very important stretch for this team, and it just shows the type of character we have on this team, as far as always believing."

Butler, Brendan Haywood, and Jamison each had buckets, and Stevenson hit a three with 1:08 left to knot the game, 79-79. The final minute then became a lead-trading affair, with the teams calling a timeout after most baskets.

Garnett followed his own shot for a tip-in, which Butler answered with a three-point play. Pierce then was fouled on his own drive, and made two free throws to give Boston an 83-82 edge with 25.9 ticks left.

But those were the final Celtics points, as Butler again came up big -- he made a one-handed layup from the right side, managing to loft the ball over Garnett's outstretched arms.

That came with 19.6 seconds remaining, and Garnett failed to hit a turnaround jumper for Boston on its ensuing possession. Butler got the rebound, was poked in the eye on the play, and was fouled. He made both free throws for an 86-83 Wizards lead.

"The game was close and there was just some opportunity for myself to get more aggressive and to make some big-time shots," Butler said. "My teammates were looking for me to step up and they were finding me on the floor, and we just made some big shots."

Boston took the ball with 8.3 seconds left, but Allen's three-point attempt was off the mark, and Stevenson grabbed the rebound to seal the win. The Celtics' loss was as much a collapse as anything, as Washington closed the game with a 25-6 run.

"I don't think we stopped playing, we definitely didn't stop playing," Garnett said. "We got our set plays that we go to, we went to them, we didn't hit shots when we needed to, didn't get stops when we needed to. It's as simple as that...I felt like when we needed stops we didn't get stops and it cost us."

The teams played a tight opening quarter that finished with an 18-18 score after two Stevenson free throws. They continued to trade baskets and the lead in the second stanza, as Allen hit a jumper at the buzzer to send the Celtics into intermission with a 37-35 edge.

Boston took a 63-59 advantage into the final stanza, and built a substantial lead with a 14-4 run to start the fourth. Eddie House made a three and a jumper back-to-back to give Boston a 77-63 lead halfway through the quarter.