LOS ANGELES -- LA Clippers point guard James Harden said he still has something to prove during the postseason in his highly productive career.

With Kawhi Leonard out for Game 1, Harden had his best first half as a Clipper, scoring 20 of his 28 points to help L.A. build a 29-point lead en route to a 109-97 win over the Dallas Mavericks at Crypto.com Arena on Sunday.

"I can score with the best of 'em," Harden said. "Still can score with the best of 'em. My role for this team is just generating really good shots and making guys' jobs easier. And then when my number to score is called, then you score the basketball. Obviously, Kawhi is out, so my playmaking and my volume is going to go up a little bit more, and took advantage of it."

Despite going without Leonard in the first-round series opener because of inflammation in his surgically repaired right knee, the Clippers put together one of their most inspired performances of the season. Ivica Zubac set the tone early inside and finished with 20 points and 15 rebounds.

The energy and activity on both ends from Russell Westbrook and Terance Mann were critical. And Paul George scored 11 of his 22 points in the fourth quarter to help close it out.

But it was Harden's first-half outside shooting that really provided the Clippers with a different element. Coach Ty Lue spoke to Harden in April when Leonard missed the final eight regular-season games about needing him to score more.

Harden scored 20 in a win over the Denver Nuggets and 22 in a come-from-behind win over the Cleveland Cavaliers late in the season. That carried over to Game 1, when Harden was aggressive and looked for his shot, something he shied away from on several occasions this season as he has tried to be more of a playmaker.

"A huge element," Lue called Harden's scoring for the team. "When he's scoring the basketball and making the right play, it's huge. He understands that he doesn't have to do a lot of heavy lifting with Kawhi and PG both on the floor. But if one of those guys are out, he has to step up and be aggressive to score the basketball. That is what he has been doing for us of late. I thought he really set the tone early."

Harden scored 42 or more points in two games during Philadelphia's Eastern Conference semifinals loss to Boston last year. But in the team's losses in Games 6 and 7, he shot only 7-for-27 and had combined for 22 points and 16 assists. He had nine points, seven assists and six rebounds while shooting 3-for-11 in Philadelphia's 112-88 loss in Game 7 at Boston.

On Sunday, Harden didn't just score, he also posted eight assists. All told, he scored or assisted on 49 points for the Clippers, according to ESPN Stats & Information research.

With Leonard's status for Game 2 uncertain, Harden may have to help carry the scoring load again.

"James was great," Zubac said. "We needed him and he played great. He is one of the greatest scorers this game has seen. He can do that on a nightly basis. It's just the role is different for him in this game and [with Leonard out], we need him to score more and that's what he did and we all know he can do that."