Oklahoma City went up 105-90 with 7:45 left, but the Blazers rallied late on.
With the game tied, Damian Lillard hit a 37-footer at the buzzer and finished with a career-playoff-high 50 points. He also broke the franchise record with 10 3-pointers.
Paul George scored 36 points for the Thunder and Russell Westbrook added 29 points, 11 rebounds and 14 assists.
Portland advances to the Western Conference semifinals to face the winner of the series between the Denver Nuggets and San Antonio Spurs.
Top Welcome Offers In Canada
Game 5 Update – The Portland Trail Blazers beat the Oklahoma City Thunder 111-98 on Sunday night to take a 3-1 lead in their series.
C.J. McCollum scored 27 points, with Damian Lillard adding 24 points for the Trail Blazers.
Paul George had 32 points and 10 rebounds for Oklahoma City, but it was a struggle for Russell Westbrook, who scored just 14 points on 5-for-21 shooting. He missed his final 10 shots and was 0 for 7 with one point in the second half.
Portland have the opportunity to close out the series Tuesday night on home ice.
Game 4 Update – Oklahoma City Thunder beat the Portland Trail Blazers 120-108 on Friday night to cut their series deficit to 2-1.
Russell Westbrook had 33 points and 11 assists for the Thunder. Paul George scored 22 points, Jerami Grant had 18 and Dennis Schroder 17.
Damian Lillard scored 32 points, C.J. McCollum had 21 points and Enes Kanter added 19 for the Trail Blazers.
The Thunder made just 10 of 61 3-pointers in the first two games in Portland. They made a significant improvement with 15 of 29 in Game 3.
Oklahoma will also host Game 4 on Sunday night, as they look to level the series.
The Oklahoma City Thunder beat the Portland Trail Blazers 120-108 to take game 3 and cutting the Blazers series lead to 2-1.— NBA Updates (@NBAUpdates100) April 20, 2019
Russell Westbrook lead the Thunder with 33 points, 11 assists, and 5 rebounds#NBAPlayoffs pic.twitter.com/YdSoKhVwwj
Game 3 Update – The Portland Trail Blazers moved into a 2-0 lead in their best-of-seven playoff series against the Oklahoma City Thunder with a 114-94 victory on Tuesday night.
CJ McCollum scored 33 points for the Blazers, for who Damian Lillard added 29 points (adding to his 30 points in the 104-99 win on Sunday).
Paul George scored 27 points for the Thunder, despite his right shoulder being covered with kinesiology tape. Russell Westbrook put up 14 points, nine rebounds and 11 assists. The Thunder were 5 of 28 from the perimeter.
The series now heads to Oklahoma City for Game 3 on Friday.
Game 2 Update – Having been swept by New Orleans Pelicans last year and the Golden State Warriors the year before, Portland Trail Blazers made a winning start to the 1st Round series against Oklahoma City Thunder with a 104-99 win.
The Thunder swept the Blazers 4-0 during the regular season, so this was a game the Blazers really needed to win to stop that momentum.
Damian Lillard scored 30 points for the Blazers, with Paul George (who had been a doubt with a sore shoulder) throwing 26 points for the Thunder. Worryingly for the Thunder, Russell Westbrook appeared to hurt his right ankle in the final quarter and grimaced while trying to walk it off.
Thunder's Russell Westbrook continues his "next question" stand-off with OKC reporter on the podium after Game 1 loss to Blazers pic.twitter.com/3gWku9eXh5— Ben Golliver (@BenGolliver) April 14, 2019