The Raptors very nearly spoiled what was the point guard's finest performance — in a playoff series full of them — while holding on for a 115-113 victory over the Brooklyn Nets.
Lowry poured in 36 points in the victory that gave the Raptors a 3-2 lead in their best-of-seven playoff series.
"He is great, he did a great job," Raptors coach Dwane Casey said. "But this game tonight, we have got to learn from it because there are so many learning experiences from tonight's game. Having the lead, (handling) prosperity, embracing the pressure.
"Kyle. . . 36 points is huge. Huge for us."
DeMar DeRozan added 23 points, while Jonas Valanciunas finished with 16 and Greivis Vasquez added 15.
Amir Johnson chipped in with 11 points for the Raptors who gave up a 26-point lead in the fourth quarter, making for some tense moments at the ACC, but held on for the victory.
When asked to describe the emotions of a fourth quarter that saw the Nets score 44 points, Casey answered: "You wouldn't want to hear it."
The series heads back to Brooklyn's Barclays Center for Game 6 on Friday, and a victory there would send them to a second-round series against the Miami Heat. A Game 7, if necessary, would be Sunday in Toronto.
The Raptors controlled the game through the second and third quarters, when it seemed they could do no wrong, and led by 26 points twice late in the third.
They headed into the fourth up 91-69 and appeared poised to cruise to an easy victory, but the Nets had plenty of fight left, tying the game at 101 on a three-pointer by Joe Johnson with 3:16 to go, stunning the crowd.
Lowry drained the go-ahead three and then scored on a driving hook shot to put Toronto up by three points with 27 seconds left. A three and foul shot by Anderson pulled the Nets to within a point, but Andray Blatche — with Lowry running right at him — turned the ball over on a backcourt violation sealing the Raptors' victory.
"He's a helluva player," DeRozan said of Lowry. "It's just that dog in him. . . Every time he's out there on the court, understand, I'm going to give my best effort, because I know he's going to do the same."
Lowry, playing with his right knee in a protective sleeve after injuring it in Game 3 in Brooklyn, has been solid all series, but took it to another level Wednesday, providing all kinds of highlight-reel plays.
There was the diving three at the halftime buzzer. There was the 85-foot outlet pass that found an unmarked Terrence Ross under the basket.
But the point guard was particularly big down the stretch, taking charges and slicing through the Nets' defence for tough buckets.
"When we needed a big shot, No. 7 came through. Kyle was unbelievable," said Raptors forward Chuck Hayes. "There's nothing more you can say. He's doing it at the right time on the biggest stage.
"We need an answer, we call Kyle. Kyle will figure it out."
It was the kind of game the Raptors would have coughed up down the stretch last season, and Casey said the team does take something from holding on for a win.
"But we can't live that way. Our history has been pretty good in the fourth quarter, but tonight, for whatever reason, they flipped the switch and flipped the script," the coach said.
Joe Johnson led the Nets with 30 points, while Mirza Teletovic added 17, and Deron Williams and Alan Anderson finished with 13 apiece.
The teams split the first two games in Toronto, and did the same in Games 3 and 4 in Brooklyn. A Game 7, if necessary, would be Sunday in Toronto.
"One game at a time and we have to take care of home," said Pierce. "I think we will play better on Friday at home and we will see them back here on Sunday."
The capacity ACC crowd of 20,393 that included Drake and rapper 50 Cent — who dipped his head when the camera was on him to show fans his "Northern Uprising" hat — was loud all game long, from the moment the fans sang along to O Canada to the final buzzer.
The arena was a sea of white, as fans wore their white "We The North" T-shirts. They mocked the Nets by chanting "Broo-klyn!" the traditional chant at the Barclays Center.
The Nets even took note, posting on the team's official Twitter account: "#Nets fans take note- this is what a playoff crowd sounds like..set your DVD and take notes #RAPTORSvNETS."
Despite the rain and chilly temperatures, some 4,500 fans jammed into Maple Leaf Square outside the ACC to watch the game on the big screen. They were given rain ponchos. Some 1,200 fans were also given black and gold OVO/Raptors lint-rollers, a nod to Drake using a lint-roller while sitting courtside during Game 2.
An array of Toronto sports celebrities took the stage, including Toronto FC's Jermain Defoe, Michael Bradley and Julio Cesar, and former Raptors Morris Peterson and Jerome Williams.
"I've never seen support like this. This is special," Defoe said in an on-stage interview. Cesar, wearing a No. 7 Raptors jersey, yelled "Let's go Raptors!"
This series has been spirited from Day 1 when Raptors GM Masai Ujiri took the stage and dropped his famous F-bomb about Brooklyn.
An enterprising man outside the ACC on Wednesday was selling F--- Brooklyn buttons, three for $5. Fans were wearing the same on T-shirts at the game.
Johnson led the way with nine points for Toronto in a first quarter that saw neither team lead by more than six. The Raptors ended the quarter with a 10-2 run capped by a Lowry three-pointer that put Toronto up 28-25 going into the second.
The Raptors trailed by four points with just over five minutes to go in the second, but finished the quarter on a 26-4 run capped by Lowry's three, part of a 13-point performance in the quarter for the point guard. The Raptors went into the locker-room at halftime buoyed by a 62-44 lead.
The third quarter has been the Raptors' nemesis in this series, but not so on Wednesday. They didn't take their foot off the pedal, shooting 58 per cent to twice go ahead by 26 points. Toronto went into the fourth with a 91-69 lead.