BOSTON -- After Sunday's loss to the Los Angeles Lakers, Celtics coach Doc Rivers lamented that, above all, his biggest disappointment was that Boston had seemingly lost its ability to generate the big stop when it mattered most.

Fast-forward to Wednesday night with the Celtics clinging to a three-point lead in the final minute against the Miami Heat. Dwyane Wade, the six-time NBA All-Star who was having a monster night that would see him finish with 30 points, 13 assists and 5 rebounds, ran off a screen from Udonis Haslem as he tried to get to the basket. Instead, Tony Allen, the sixth-year forward thrust into the starting lineup with Paul Pierce sidelined, picked Wade's pocket and was immediately fouled.

Allen made both free throws with 36 seconds remaining to help Boston emerge with a 107-102 triumph over the Heat at TD Garden.

“[Wade] was having a great night tonight, he was cooking," said Allen. "I just had to try to keep my head and, whenever my number got called, I just focused in on trying to get a stop. I was fortunate enough to go under the pick-and-roll because it was higher than the 3-point line. I knew he was about to split, so as soon as he was about to split, I just reached my left hand out there and got the steal, hit the two free throws, and that was the game."

It all sounds so simple. But consider this: Wade had absolutely torched the Celtics as the ball-handler in the pick-and-roll this season. According to ESPN Stats and Research, Wade shot 50 percent (9 of 18) as the primary ball-handler in pick-and-roll plays during the first two meetings. What's more, he hit all five field-goal attempts and added five assists off the pick-and-roll during the first three quarters of Wednesday's meeting.

But in the fourth quarter, the Celtics locked him down.

Wade didn't attempt a single shot off the pick-and-roll in the fourth quarter, generating just one assist and turning the ball over twice, including Allen's pivotal steal. Just the sort of defense Rivers had been looking for Sunday.

“I needed that, I needed that confidence," said Allen. "I was struggling offensively tonight, but my bread and butter is defense and sticking with those guys."

Rivers admitted a player like Allen is a luxury.

"Well, we can say, ‘You guard [the opposing team's scorer]’ every night," said Rivers. "And every team -– there’s not a team in the league that I can think of without a good 2 or 3 on their team. So every night you can say, ‘Tony, you guard this guy.’ It helps our defense."