Heat beat Spurs in opener for first time in 4 years, and have won six of their last seven home games, including two in a row this year.
Heat forward Chris Bosh has been sidelined since April 10 with a blood clot in his lungs.
Miami also won in Memphis on Thursday night, defeating Memphis 115-102 to advance to a second round of the playoffs.
Heat coach Erik Spoelstra said he’s not sure how long Bosh will be out, but Bosh’s absence is a significant blow to the Heat.
“We were playing really well,” Spoelstras said.
“It’s tough to be out for so long.
It’s not easy, but we’ll see how he is and see what the prognosis is.
But at the same time, he has to do the right things and keep doing the right thing.”
Injuries to other Heat players also have hurt the team this season.
“I feel like it’s a little bit of a blow,” forward Mike Miller said.
In addition to Bosh, James Johnson and Chris Andersen are also out with injuries.
Bosh has played in all but two games this season, scoring 23.5 points per game.
He has been averaging 28.7 points on 47.4 percent shooting over the last two months.
Miami was 10-5 on the road this season after winning nine of 10 at home.