Porter departed Game 3 of the Western Conference finals midway through the second quarter and was later ruled out with what the team described as left foot soreness.
X-rays on the foot were negative. The team officially listed Porter as questionable on the 6:30 p.m. ET injury report on Monday.
The short-handed Warriors managed without Porter. Stephen Curry scored 31 points and added 11 assists as Golden State posted a 109-100 victory to secure a 3-0 series lead over the Dallas Mavericks on Sunday night.
Porter sustained the injury when he landed after going up for a layup. Porter came up hobbling, and was fidgeting with his left foot at the next stoppage -- a pair of Dallas free throws. Porter tried to play through the pain, but called to be subbed out just a few moments later.
During the Warriors' subsequent timeout, Porter limped back to the locker room with trainers. After undergoing X-rays, he was running up and down the hallway testing out his foot.
Porter missed Game 6 of the Western Conference semifinals with right foot soreness.