Shai Gilgeous-Alexander produced 29 points, nine rebounds and nine assists to lead the Oklahoma City Thunder to a 117-95 win over the visiting Dallas Mavericks in Game 1 of their Western Conference semifinal series on Tuesday.

Gilgeous-Alexander shot 8 of 19 from the floor but 11 of 13 from the free-throw line in his first career second-round playoff game. The Thunder became the youngest team in NBA history to win a conference semifinal game.

Kyrie Irving scored 19 points and Luka Doncic finished with 19 points and nine assists for Dallas.

Less than five minutes into the third quarter, the Mavericks cut a 12-point Thunder lead to one on Irving’s 3-pointer off a feed from Luka Doncic.

Oklahoma City outscored Dallas 51-30 the rest of the way.

“I think it’s a muscle we’ve built at this point,” Thunder coach Mark Daigneault said of the poise his team showed in responding when Dallas cut his team’s lead. “We’ve had to endure a lot of those situations during the course of the season. I think a lot of it comes from respect for your opponent.”

The Thunder quickly answered Irving’s trey out of a timeout, with Isaiah Joe draining a 3-pointer to kickstart a 14-4 run over the next three minutes.

Gilgeous-Alexander assisted on two of the Thunder’s four 3-pointers during the run, then added the exclamation point on the stretch by sinking a 3-pointer from the top of the key to send the home crowd into a frenzy.

Before the game, Doncic heaped praise on Oklahoma City’s Luguentz Dort, calling him one of the top perimeter defenders in the NBA.

Dort showed why during the key sequence, knocking the ball away from Doncic near midcourt, diving to collect the ball before quickly finding a streaking Joe, who fed it up to Jalen Williams for a dunk.

Dort helped the Thunder hold Doncic to 6-of-19 shooting, including 1-of-8 from beyond the arc.

“They’re a great team, great defensive team, great offensive team, so it’s not going to be easy at all,” Doncic said. “We’ve got to play very good basketball – focused basketball – for 48 minutes.”

The Mavericks went nearly four minutes without a field goal late in the third as Oklahoma City stretched its lead as high as 15 before Dallas cut it back to 10 with two baskets in the final 30 seconds.

Oklahoma City’s Chet Holmgren had 19 points, seven rebounds and three blocks, Williams added 18 points and Aaron Wiggins had 16 off the bench, including 12 in the second quarter.

The Thunder scored 22 points off Dallas’ 16 turnovers.

The Mavericks shot just 39.3 percent, while the Thunder hit 44.9 percent.

Game 2 of the best-of-seven series is scheduled for Thursday (9:30 p.m. ET on ESPN) in Oklahoma City.