McCollum had six of his 21 points in overtime, Damian Lillard scored 33 points and the Trail Blazers defeated the Memphis Grizzlies 112-106 on Monday night.
"I wasn't very good," said McCollum, who was 7 of 19 from the field at the end of regulation. "I fouled. I gave up some points to Mike Conley. Didn't make shots. But I just had to stick with it. They need me to score. They need me to execute down the stretch and have the confidence to take and make good shots."
The game would not have reached overtime if not for a strange sequence at the close of regulation.
Memphis held a 102-100 lead after Tony Allen split a pair of free throws for the Grizzlies with 7.6 seconds left.
On the ensuing possession, Lillard launched a 3-pointer that missed, McCollum tapped up the rebound, but that that was off the mark before another tip went through the net as the horn was sounding.
Allen Crabbe was given credit for the basket, but replays showed Memphis' Jeff Green actually was the one with his hand on the tip that went through.
And after that, officials reviewed the play to make sure of two things - that the shot was off in time, and there was no basket interference.
Eventually, they ruled the basket good, sending the game to the extra period.
"We got the rebound, we got a tip-in, and I just saw all black jerseys down there," Lillard said of the final play in regulation. "There was a little bit over a second (left), and I thought: 'We've got a chance to tip something.'"
As for Crabbe, he said: "I tried to make a play on the ball, and it went in. They gave me the two points, so I'm going to take credit for the tip-in."
Conley led Memphis with 27 points, while Zach Randolph added 26 points as Memphis lost its second straight overtime game.
Marc Gasol scored 11 points before leaving late in the first quarter with a right foot injury. He did not return. Mario Chalmers and Green had 12 apiece for Memphis.
Gerald Henderson scored 16 for Portland, while Crabbe finished with 13.
The game was close throughout with both teams' biggest leads reaching six points. There were 18 ties and 17 lead changes.
After McCollum's first three baskets of overtime, Memphis tried to claw back and appeared to have a chance. Trailing 108-106, Allen was on a breakaway with about 10 seconds left but missed the layup on the other end, and the Grizzlies never got closer.
"That's one I'd like to have back," Allen said of the game. "I want to take this one on the chin personally."
