Before tipoff, Jazz coach Tyrone Corbin said Favors' return "is huge for us. ... We look forward to getting him back on the floor."
Favors had not played since Nov. 30 at Oklahoma City.
"I don't know if I'm 100 percent," he said. "I just want to go out there and play hard. Basically do what I do and get some of the rust off."
According to Favors, Corbin told him to "just go play and, if I feel any discomfort, tell him and I'll come out."
Favors appeared to pass his first test against the rugged Spurs.
"San Antonio is a great opponent and we need his size and shot-blocking ability at the basket," said Corbin, who promised to be careful with Favors.
"We'll watch it a little bit. He's been off for five games now, so we'll see how it's going. He thinks he's ready to play extended minutes, but we'll look at it."
Mostly, Corbin was concerned about Favors' conditioning, after not playing for almost two weeks.
"Timing and getting [his] wind back," the Jazz coach said. "... Typically, after a couple of days, you lose a little of your wind."
Favors entered the game for the first time with four minutes left in the first quarter and Utah trailing 19-12.
Moments later, Favors came up with a steal, leading to a three-point play by Gordon Hayward. Then, he cut off Tiago Splitter, who threw the ball away. On the other end, Randy Foye nailed a 3-pointer to narrow San Antonio's quarter-long lead to 26-22.
Favors scored his first basket 90 seconds into the second quarter, making it 33-26.
He ended up playing 5:48 in the second half and another 6:14 starting late in the third quarter and ending early in the fourth.