The shooting guard, who moved to the Mavericks last summer, played in all 82 games during the regular season, averaging 19 points per game.
The team's top scorer told NBA.com: "He's a big part of why we're back in the playoffs. He hasn't missed a game. He hasn't missed a practice. We need him to play well if we want to advance in the playoffs."
The Mavericks, who finished the season as the eighth seeds in the Western Conference, will face the San Antonio Spurs in the first round of the playoffs.