Luka Doncic acknowledged "I've got to be better" after the Dallas Mavericks were beaten by Oklahoma City Thunder in Game 1 of their Western Conference semi-final series.

The Thunder, who swept the New Orleans Pelicans aside in their first-round series, built on that momentum with a 117-95 victory at Paycom Center.

Although, it was a day to forget for Doncic, who registered just 19 points on six-of-19 shooting as he ended a streak of 24 successive playoff games with at least 20 points, while he also had five turnovers.

Struggling with a knee injury and tightly marked by Oklahoma's Lu Dort, the five-time NBA All-Star was also just one-for-eight from three-point range, making it five-of-35 over the past four games.

That is the worst percentage (14.3 per cent) for any player with at least 30 attempts over a four-game streak during the postseason.

"[We've] just got to move onto the next one," Doncic said. "I've got to be better, we've got to be better. We've got to focus. They're a great team, a great defensive team, so it's not going to be easy at all."

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

The youngest team in NBA history to win a playoff series following their triumph over the Pelicans, Oklahoma made it five straight wins in the postseason with Shai Gilgeous-Alexander scoring 29 points along the way.

The Thunder have only conceded 90.6 points per game in the playoffs, the fewest by any team across five games in the postseason since the San Antonio Spurs in 2016.

"[The defence is] 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 going to start on that end.

"Obviously, we have some really talented players at that end of the floor, but we also like to do it together and not just rely on those guys."