LAKE BUENA VISTA, Fla. -- For the second straight game, the Philadelphia 76ers appeared to have a game in hand through three quarters.

Then the fourth quarter happened.

After giving up 46 points in the final period and losing in stunning fashion to the Indiana Pacers in their first game Saturday, Philadelphia allowed the San Antonio Spurs to drop 43 on them in the fourth Monday, only to be bailed out by a Shake Milton 3-pointer with 6.1 seconds to go and escape with a 132-130 victory.

"I think it stinks," Sixers coach Brett Brown said afterward of his team's lackluster fourth quarters. "I think it's not anything that we believe in or talk about. We were very lucky to win tonight. In two closeout periods, against Indiana it was 46, tonight it was 43 ... that's not going to get anything of any importance done.

"It is well within our reach, immediately, to flip the switch. We have to have an immediate paradigm switch and an admittance we can't afford to pick and choose. The past two games, we have done that. I give credit to Indiana and tonight to the Spurs ... but in general, it ain't going to get it done. It's not who we are, and it needs to be fixed, and fixed it will be."

After letting T.J. Warren score 53 points on Saturday, the Sixers allowed DeMar DeRozan to score 30 on Monday, and Rudy Gay added 24 points off the bench.

"We got to do a better job," Joel Embiid said. "We want to be the best defensive team in the league, so we have to just take the challenge. It's not just the fourth quarter. It's the whole game. The last two games, we haven't been able to keep our man in front of us, and I have to do a better job of protecting the rim and making sure I can correct some mistakes."

The fact that this conversation was being had after the game was hard to believe, given the talent gap between the Spurs and 76ers on a normal day. Plus, with the Spurs down several key players because of injury and on the second half of a back-to-back, that gap was even larger.

After Philadelphia finally took control of the game in the third quarter once Joel Embiid, who finished with 27 points, 9 rebounds and 5 assists, began asserting himself, it seemed that order had been restored, but the Spurs roared back in the fourth quarter with a 40-22 run to take a four-point lead with 90 seconds to go.

Eventually, San Antonio's lead was whittled to two with 10.4 seconds remaining and the Sixers inbounding the ball. With the Spurs sending a double-team to Embiid in the post, Milton -- who on Saturday both played poorly and got in a fight with Embiid between the first and second quarters -- was left all alone and calmly drained what turned out to be the winning 3-pointer, saving Philadelphia from what would have been a second straight embarrassing loss.

"We needed it," Brown said of Milton, who finished with 16 points on 6-for-9 shooting with three assists and a turnover after going scoreless against the Pacers. "... He wasn't guarded, they threw him the ball, and he didn't think. He just shot it. Shake, it's quite clear he's an articulate and intelligent man. And the poise and grace he goes about his business with was reflected in that moment. He was very calm. I thought he was great tonight."

If there were any concerns about Milton and Embiid not getting along after their tiff Saturday, both took to social media after Monday's victory to celebrate.

For San Antonio, it was a crushing loss on a night that could have seen the Spurs move within one game of the Memphis Grizzlies for the eighth playoff spot in the Western Conference. The Spurs are trying to make the playoffs for a 23rd consecutive season.

"Everybody is sick in the stomach," Spurs guard Dejounte Murray said. "We fought so hard, and we had that game in our hands."