Allen, who misfired on 11 of his first 13 shots of the night and missed a pair of free throws, drilled a pivotal 3-pointer with 41.3 seconds remaining in the extra session as Boston rallied from its only deficit of the night.
"We got him good shots," said Rivers. "Listen, he had one of those nights. I think he missed two technical foul shots, probably for the first time in his career, who knows? But shooters shoot and eventually you just have to think the odds [are with you]. Every miss meant the odds were on our side more [that Allen would make the next one] is the way I was looking at it.”
Allen, who's shooting a career-worst 35.1 percent from 3-point land this season, has connected on just three of his last 17 shots from beyond the arc. But it didn't matter Friday, he made the last one.
"Ray is one of the great shooters of all time -- he’s right behind me," joked Celtics captain Paul Pierce. "I told him that in the huddle. He had the looks, but the one we needed he was able to knock it down. That’s how much we believe in Ray.”
Like any good shooter, Allen refused to pin the blame on himself. As Rivers noted, great shooters think the next shot is always going to go in, and that's what separates them from good shooters, who might typically stop firing away when the shots won't fall.
"There wasn't anything wrong with my form or my mechanics," said Allen. "[The shots] just wouldn't go in."
Allen finished with nine points on 3-of-14 shooting with four assists and three rebounds over a team-high 43 minutes.
Opposing View: 'We lost him'
Trail Blazers head coach Nate McMillian lamented the fact that his team let Allen get open for the game-changing 3-pointer in the extra session.
"We lost him early," said McMillian. "I think a possession before that he missed a 3, but then we lost him again, and he hit that same shot. You know he’s gonna knock that shot down. They’re looking for him. He had time to see the rim and... that second one, he doesn’t [usually miss] again.”
On the positive side, McMillian raved about Andre Miller, who kept injury-depleted Portland in the contest by pouring in a game-high 28 points with eight rebounds and eight assists over 47 minutes.
“I thought he kept us in it, helped us fight back to take the lead," said McMillian. "[Boston] ended up being aggressive, pressuring him to bring the ball down the floor. He made some big plays, we tried to go to him. I thought that last 3 he took, he had heavy legs. I think he wanted to try and go, but just couldn’t on that possession."
Miller admitted his overtime 3-pointer with 1:21 to go might have been ill-advised given his heavy legs, but he felt like he could put the game out of reach. He didn't see any silver lining in the loss.
"There’s no moral victories, we let another one slip away," said Miller. "We talked about our execution down the stretch, we had turnovers at the wrong time, and that’s the game.”
Doc's Opinion: Not a pretty win
Rivers acknowledged it wasn't the prettiest win of the 2009-10 season, especially as the Celtics watched another double-digit lead evaporate while nearly letting the visitors escape with a win. But he found plenty of positives.
"It was a good victory for us in the fact that, offensively, we couldn’t ask for better shots," said Rivers. "We missed layups, free throws. I think in the second quarter we had that three layups in a row that we missed. [Rajon] Rondo missed a big layup down the stretch. We missed wide-open shots. We missed free throws. But our defense hung in there. And what we’ve been talking about the last two or three days is that, at some point, we’ve got to turn back into that defensive team that doesn’t rely on great offense.
"I believe we’re going to be great offensively, the numbers say it. Field goal percentage and all that. We’re going to get good shots. But when your offense fails, you’ve got to be able to be a great defensive team and get stops. And that’s what this game turned into. So it wasn't pretty, but, in some ways for us, the way we won may have been better for us.”
Scal on the shelf
Brian Scalabrine missed Friday's game with what was dubbed a "sore right shoulder," but, after the game, he told WEEI.com's Jessica Camerato that it's actually a separated shoulder suffered earlier this month against the Miami Heat.
Rivers indicated the reserve forward will be sidelined through at least Monday's game against the Clippers, while Scalabrine suggested Thursday's visit to Orlando is his current target date to return.