Allen scored a season-high 36 points, including eight 3-pointers, and the Celtics withstood a late Toronto rally to beat the Raptors 94-88 on Sunday afternoon, snapping a four-game losing streak.
"When Ray gets it going, that's our focus," Boston coach Doc Rivers said. "Feed the pig, that's what we always say. He was the hot guy, so we want to keep feeding him."
Allen, who made a career-high 10 3-pointers against Charlotte on April 14, 2002, went 8-for-10 from 3-point range Sunday, making his first six attempts.
Allen wasn't sure what to make of Rivers' farmyard metaphor.
"We don't want the pig to get as fat as it possibly can," Allen said with a laugh. "One day you have to slaughter the pig."
Paul Pierce said the Celtics know when to give Allen his turn at the trough.
"When you see a player having a good night like that, it's our duty as other players to try and get him the ball," Pierce said. "We just rode his hot hand tonight."
Allen had been held below 20 points in 10 of Boston's past 11 games, but Rivers never worried about him losing his touch.
"It's funny, I get so many calls saying 'What's wrong with Ray?' and I say 'There's nothing wrong with Ray, he's a great shooter, he'll be a great shooter again and eventually make them,'" Rivers said. "That's why Ray is great and a lot of other players in the league are good. A lot of players will have three or four games like Ray had and go away for a month. Ray believed the next shot had to go in. He knows he's a great shooter and we want him to keep shooting."
"It was the old us for a lot of stretches today, so I was happy with that," Rivers said.
Leading 75-55 to start the fourth, the Celtics allowed Toronto to get back in it with a 17-5 spurt that cut the gap to eight points, 80-72, with 5:52 left.
"We kind of let our guard down and then we couldn't control them," Rivers said. "They closed the game out far better than us."
Boston held firm until Andrea Bargnani's 3-pointer made it 88-83 with 1:36 left. Jamario Moon missed a 3 on Toronto's next possession before Pierce's jumper with 40 seconds remaining sealed the win for Boston.
"There's no relief there," Rivers said of ending the slump. "We could have played better and we know that. There was more good than bad by far but we want more good all the time."
Still, the mood in Boston's locker room was light, with Allen, Pierce and Sam Cassell crowding their way into Garnett's media scrum and jokingly asking the star forward to speak up.
When he did speak, Garnett echoed Rivers' assessment.
"It's always good to win but we know we're better than what we're playing," he said.
Bargnani led Toronto with 17 points while Chris Bosh and Moon each had 15.
The Raptors, who visit Boston on Monday night, are 0-3 against the Celtics this season.
Toronto shot a season-high 55.6 percent in Wednesday's 103-82 victory over Memphis, but struggled against Boston's stingy defense, shooting 28-for-74 (37.8 percent).
Pierce injured his right knee in a first-quarter collision with teammate Brian Scalabrine and sat out the final 7:25 of the first quarter before returning to start the second. Pierce wore a protective sleeve on the knee in the second half.
"We're a little concerned by that because I didn't think he moved well the rest of the game," Rivers said. "I was scared to take him out of the game because I thought if I took him out in the second half, I probably wouldn't be able to put him back in."
Pierce, who hyperextended the same knee last month, wasn't sure whether he'd be able to play Monday.
"We'll see how it feels after the plane ride and some rest and treatment," he said. "Hopefully it will get better overnight."
Scalabrine and Toronto forward Joey Graham each picked up technical fouls in the second after a shoving match under the Boston basket escalated into a heated face-to-face argument at midcourt.
Toronto led 12-6 after the first three minutes, but Allen made four 3-pointers as Boston responded with a 16-0 run, putting the Celtics up 10, 22-12. Allen made one more 3-pointer before the quarter ended, giving Boston a 32-30 lead after one.
Allen made the only shot he took in the second, and Boston got 11 points from its bench to lead 54-41 at the half.
Toronto guard Jose Calderon returned to the starting lineup after missing the previous four games with a strained right hamstring, scoring six points in 22 minutes. He went 4-for-4 from the free-throw line and has made 79 straight dating to last season, the third-longest streak in NBA history. Minnesota's Micheal Williams holds the record, making 97 straight free throws in 1993.
Neither Calderon nor forward Jermaine O'Neal, who has missed seven straight games with a sore right knee, will travel to Boston for Monday's game.
Boston was without guard Tony Allen (right ankle) and center Kendrick Perkins (right shoulder). ... Toronto made more free throws (19) than field goals (16) through the first three quarters.