The Spurs host the Boston Celtics on Thursday as both teams go for their sixth straight win.

San Antonio (9-6) lost six of its first 10 games to post the worst start in the Tim Duncan era.

An ankle injury caused Duncan to miss two victories during that stretch, but he's been a key factor during the current five-game winning streak, averaging 20.6 points and 9.8 rebounds. He's led the team in scoring in three of the wins, including a 97-89 victory over Philadelphia on Sunday.

The Spurs held the 76ers to 39.3 percent shooting and gave up fewer than 90 points for the third time during the win streak. They are yielding an average of 91.8 points in the last five games - seven fewer than the first 10 games.

"We really shouldn't care that much about winning five in a row," said Manu Ginobili, who returned Sunday after missing five games with a strained groin and finished with eight points and three turnovers in 17 minutes.

"It's always good. It helps your confidence, and of course your standings, but we still believe we've got a long way to go."

Ginobili and the Spurs may be hesitant to make too much of the winning streak given the quality of the opponents. Three of the teams they defeated have losing records and the other two - Houston and Milwaukee - have spent much of the season hovering around .500.

San Antonio's upcoming schedule should provide a bigger test, with home games against division leaders Boston and Denver before Monday's visit to Utah, which has won six of seven.

However, not all the Spurs see the upcoming game against the Celtics (14-4) as a measuring stick.

"Right now, neither team is going to be as sharp as they'd like," Richard Jefferson said. "I think both teams are going to be a lot better later in the season. ... We're standing firm with (coach Greg Popovich) that we're learning, we're all trying to get better from day to day."

The Spurs haven't won six in a row since Dec. 4-14, 2008.

Boston brings its own five-game winning streak into San Antonio as it continues a four-game road trip. The Celtics beat Charlotte 108-90 on Tuesday behind Ray Allen's best performance of the season.

Allen came in averaging 15.2 points but finished with 27 - he scored more than 20 in only one other game all season - and hit five of his six 3-point attempts. He had been 7 for 27 from beyond the arc in the previous six games.

"I put some baby oil on the rim," Allen said, smiling. "I said earlier I had to just put it in, just swish the ball, not even mess around with the rim. It's really all a body thing, just getting your legs in the air and being consistent."

Allen regaining his shooting touch adds another weapon to an offense averaging 107.2 points and shooting 51.6 percent over the winning streak. Paul Pierce averaged 26.0 points in the first three games of it, although he's been held to a combined 23 in the last two. He was 3 of 8 from the field Tuesday to finish with a season-low eight points.

Boston and San Antonio split their two games last season with each winning on the other team's court. The Celtics have won three in a row at the AT&T Center.