Kawhi Leonard strolled to the locker room late in third quarter, just as J.J. Barea was starting a Dallas rally that spoiled the season debut of San Antonio's forward. Leonard missed the first 27 games with a right quadriceps injury and was on a minutes restriction in his return. So there wasn't anything he could do in the fourth quarter to save the Spurs' four-game winning streak as the last-place Mavericks won 95-89 on Tuesday night in Dallas. "I understand the situation that I'm in and we're thinking about down the road," said Leonard, whose injury has been causing pain and weakness in his knee and who hadn't played in a game since Game 1 of the Western Conference finals against the Warriors.