OKLAHOMA CITY -- Dallas Mavericks superstar Luka Doncic didn't care to discuss the extenuating circumstances involved in his struggles during Tuesday's 117-95 loss to the Oklahoma City Thunder in Game 1 of the Western Conference semifinals.

Doncic, dealing with a sprained right knee and the smothering defense of Oklahoma City's Lu Dort, was held to 19 points on 6-of-19 shooting, snapping his streak of 24 consecutive playoff games with at least 20 points.

"Who cares? We lost," Doncic said when asked about the factors involved in his off night. "Just gotta move onto the next one. I've gotta be better. We've gotta be better. We gotta focus. They're a great team, a great defensive team, so it's not going to be easy at all."

Doncic, the NBA's scoring leader who sprained his knee early in Game 3 of the Mavericks' first-round series against the LA Clippers, is mired in a shooting slump. He dipped below 40% from the floor for the postseason.

He was 1-of-8 from 3-point range Tuesday as the Mavericks fell to 0-5 in Game 1s under coach Jason Kidd, dropping Doncic to 22.7% from beyond the arc during these playoffs. That includes 5-of-35 over the past four games, the worst percentage (14.3) over a four-game postseason stretch with at least 30 attempts in NBA history, according to ESPN Stats & Information.

"He had some good looks at 3," Kidd said. "So we gotta help him out, get Dort off of him a little bit more."

The Thunder, led by MVP candidate Shai Gilgeous-Alexander's 29-point, 9-rebound, 9-assist performance, rolled to their fifth straight win to open the playoffs.

Oklahoma City is allowing 90.6 points per game in the playoffs, the fewest through five games by any team since the 2016 San Antonio Spurs. The defense is led by Dort and rookie center Chet Holmgren, who had three blocks and held the Mavericks to 5-of-15 shooting on shots he contested. He also scored 19 points.

"It's where we hang our hat every night," Gilgeous-Alexander said. "Especially this late in the season, we know that if we want to win basketball games, that it's gonna start on that end. Obviously we have some really talented players on that end of the floor, but we also like to do it together and not just rely on those guys."

The Mavericks made a run in the third quarter, when Kyrie Irving seemed on the verge of seizing control of the game as he had on multiple occasions in the first round, to pull within a point. Oklahoma City responded by scoring on its next six possessions, including five 3-pointers, to stretch the lead back to double digits.

"We have to put a complete game together against this young OKC team because they have an endless amount of energy," said Irving, who finished with 20 points. "They're never gonna stop attacking."

Dallas never mounted another threat, and the Mavericks pulled their starters with 5:14 remaining, when they trailed by 22.

"It's a muscle we've built at this point," Thunder coach Mark Daigneault said regarding the poise displayed by the youngest team in NBA history to win a playoff series. "I think a lot of it comes from respect for the opponent, but we know this is a heavyweight matchup. To think that you're going to go through games or a series when they don't land on punches is just unrealistic. It's a long series. We have to be ready for a better version of them coming out."