BOSTON — Even when things are going well for the Celtics — and they most certainly are not right now — Paul Pierce looks forward to the Lakers' annual visit to Boston.

"It's always a big deal. It is for me," the Los Angeles native and longtime Celtics forward said. "We feel like it's a must-win. These are teams we're going to see in the playoffs so we're giving them psychological edge right now. That's not something that you're going to be able to turn on once the playoffs start. So we've got to turn it around right now."

And it won't be easy.

The Celtics are in a rut unlike any they've seen since assembling the New Big Three in the summer of 2007. They have lost five of their last seven and 10 of their last 16 since beating Orlando on Christmas Day, including back-to-back losses to the Magic and Atlanta Hawks.

That makes Sunday's matchup of the last two NBA champions Boston's third game in four days — all of them against top teams in the league.

"Yeah, and the Lakers are the cherry on the top for us!" Celtics coach Doc Rivers said. "It's still fun to play these games, because they're good teams and you enjoy playing them. There's no love lost, and all that stuff's good. It's good for our league. But more importantly, it's just fun in the middle of the season to have days like this."

The defending Eastern Conference champion Magic overcame a 16-point deficit to beat the Celtics on Thursday night. The Hawks beat Boston 100-91 on Friday night to complete a four-game season series sweep — Atlanta's first over Boston in 11 years — and move one game ahead of the Celtics in second place in the East.

One of the more puzzling aspects of Boston's slump is its home record. While their road mark is one of the best in the NBA — even after the recent road swing that dropped them to 16-8 — the Celtics have struggled at home, going 13-7; in their title-winning season of 2007-08, they lost only six home games all year.

"They're a tough team. They're a championship team. They still have that flavor to them," Lakers coach Phil Jackson said. "They're going to be physical and aggressive. You're going to have to play through that. That part's going to be good for the team."

When the Lakers won in Philadelphia on Friday for their third straight victory, guard Kobe Bryant was keeping one eye on the Celtics. Noting their struggles against Orlando and Atlanta, he predicted that they will have things turned around by the time their archrivals arrive.

"I'm looking forward to seeing how they answer that challenge," Bryant said. "Every time we go back to Boston, it's special, because that's where we lost the (2008) championship. All those memories come back."

Bryant has some personal motivation, too.

With 47 points Sunday — a total he's hit 29 times in his career in the regular season, but never against Boston — he would pass Jerry West as the Lakers' all-time leading scorer. Jackson noted that West averaged 39.2 points in the higher-scoring days of the NBA, making Bryant's accomplishment even more remarkable.

"That's almost unheard of now to have someone score 30 points a game as an average. The game has changed dramatically," Jackson said. "In that regard — the scoring's not there — Kobe's challenge for points, I think it's a remarkable thing. He's pursuing it, and he's aggressive as an offensive ballplayer and he's going to be scoring for a while."

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AP Sports Writer Dan Gelston contributed to this story from Philadelphia and AP freelancer Amy Jinker-Lloyd contributed from Atlanta.