BOSTON -- Before this season began, the Celtics and Raptors were pegged as the teams most likely to square off in the Eastern Conference finals for the right to the throne that LeBron James and his former team had claimed for eight straight years.
Then the season started. While the Raptors looked every bit like the team they were supposed to be, the Celtics struggled out of the gate, with a wheezing offense weighing them down. It looked like that would be the case again Friday night, as the Raptors took control through the first three quarters at TD Garden.
Kyrie Irving, though, had other ideas.
Irving finished with 43 points -- 23 of which came in the fourth quarter and overtime -- to go with 11 assists to lift the Celtics to a thrilling 123-116 overtime win.
For Boston, it was a much-needed victory in a game that easily could have been mistaken for one in late May, not mid-November.
"It's just not too often during the regular season you get to have games like this," Irving said. "So you want to take full advantage of them. They're a great test for your team on both ends of the basketball floor. A great player in the other locker room. So you've just got to be on your P's and Q's for the unknown, and that's the competition.
"The level of play raises, and you've just got to appreciate that."
Irving certainly raised his level of play and, in doing so, raised that of the Celtics as a whole.
Even with subtle improvements lately, Boston entered the night ranked near the bottom of the league in offensive efficiency (23rd), due in large part to its struggles getting to the basket.
Through much of Friday's game, that was again the case. The Celtics settled for one jumper after another, failing to either get to the rim or the foul line. After Raptors forward Pascal Siakam hit two of them to open the fourth quarter, Toronto had attempted 25 free throws; Boston had taken only 12.
But then, it appeared a light finally went off for the Celtics, especially Irving. Once he and his teammates began attacking the rim, things finally began to open up for Boston offensively.
"We need to do a better job of attacking the paint, period," Celtics coach Brad Stevens said. "Kyrie's ability to get in there is so unique. ... We just need to be better at that."
The Celtics looked like a completely different team in the fourth quarter and overtime, finally playing with aggressiveness on offense.
Asked about the offense after the game, Irving repeatedly used the word "aggressive" to describe not only how Boston played late Friday but how it needed to play moving forward.
He scored 19 points in the fourth quarter, including 11 in a row for Boston in one stretch, and made a series of increasingly difficult layups in and around the rim to keep the Celtics in the game.
"It's just a mindset," Irving said. "It's a mindset that we just have to ingrain in all of us.
"Just find that happy balance of the 3-point line as well as getting to the rim and then not taking tough 2s but taking 2s that are off the second-side action or just driving to the rim and being aggressive."
Irving's aggression was contagious Friday night, particularly for Jayson Tatum, whose performance late in the game was much more in line with how he played in his breakout rookie campaign last season.
Limited to two points on 1-of-5 shooting in the first half, Tatum had 19 points on 7-for-8 shooting in the second half and overtime.
More importantly, Tatum stopped settling for jumpers and attacked the rim. Early in the fourth quarter, he got to the rim for a layup; he had a massive dunk to pull Boston to within two with 48.7 seconds remaining in regulation; and he hit a floater in the lane midway through overtime that pushed Boston out to a multipossession lead for the remainder of the game.
"I wasn't playing well in the first half, and I just knew I had to be better," Tatum said. "I had to do my part."
Friday's win also marked an important step for Gordon Hayward, who continues to recover from the gruesome injuries to his left leg and ankle he suffered in last year's season opener. Hayward hit a season high in minutes, playing 39:03, including virtually the entire fourth quarter and all of overtime, and he also had a significant impact on the game.
A successful boxout of Siakam allowed him to get an over-the-back call and make two free throws to tie the score at the end of regulation, and Hayward then hit two free throws and a turnaround jumper on the baseline to open the scoring in overtime.
For someone still clearly working his way back into form, all of it was important. After finishing with 15 points, 5 rebounds and 5 assists, Hayward wore an ear-to-ear grin in Boston's locker room.
Hayward said he was surprised Stevens kept him on the floor as long as he did.
"I'm happy he left me in," Hayward said. "It felt good to play that many minutes. It's been such a long time since I've done that, so it's a good confidence booster."
To beat the Raptors in the playoffs -- let alone contend with the Golden State Warriors in the NBA Finals -- the Celtics will need the version of Hayward they signed in July 2017 to arrive. This performance was, in several ways, another step closer to that player returning.
With all that being said, Toronto still had its chances. Kyle Lowry was dreadful, going 3-for-12 and committing 4 turnovers while finishing with 14 points and 7 assists. OG Anunoby left in the second quarter with a sprained wrist, though the Raptors didn't seem overly concerned about the injury afterward. Danny Green was hit with a pair of questionable calls in a 35-second span to foul out with 3:43 to go in regulation, and his absence was a clear issue for the Raptors afterward. The same thing happened when a back issue forced Green out of Wednesday's loss to the Detroit Pistons, another agonizingly close defeat.
And Kawhi Leonard, who finished with 31 points, 15 rebounds, 4 assists and 3 steals in 43 minutes, had a decent look at a game-winning jumper at the end of regulation that was a couple of inches off from this having a very different outcome.
Toronto could easily be 14-2 and coming off a pair of close, emotional victories. Instead, the Raptors are 12-4 and will take a three-game losing streak with them to Chicago on Saturday night.
"I ain't really worried about [the record], whatever it is," Lowry said. "The losses, what is it, Game 16? I think we're in a good position to be 12-4. We've lost three winnable games.
"It's just a learning process."
For the Celtics, Friday should also serve as a learning process. The game changed when a steady diet of jump shots turned to one featuring a healthy dose of Irving, and to a lesser extent Tatum, getting aggressive and attacking the rim.
This time, things went in Boston's favor because of it. For the Celtics to realize their potential, playing with that aggression needs to become the rule and not the exception.