The Wizards’ Nene works against Tim Duncan and Tiago Splitter, left, during the first half. (Eric Gay/ASSOCIATED PRESS)

Coach Randy Wittman could only chuckle to himself when he heard that San Antonio Spurs all-star power forward Tim Duncan, after missing the past four games with a sore left knee, was going to make his return against the Washington Wizards.

“Why not?” Wittman said, shaking his head before the game, a tacit acknowledgment of the task his struggling team faced with or without the future Hall of Fame big man on the court — especially since the Spurs had remained the league’s hottest team.

The Spurs were without Duncan for the final 28 minutes on Saturday, after an ugly collision with Wizards swingman Martell Webster zapped much of the energy out of AT&T Center and had players on both sides worried as he left the game with the assistance of teammates DeJuan Blair and Stephen Jackson. The Wizards took advantage of their shell-shocked opponent, trimming a 27-point deficit down to six in the fourth quarter but were unable to overcome a miserable first half and lost their fourth game in a row, 96-86.

“It was night and day. Second half, we play, we have pride and we showed them,” Nene said. “I’m happy with the team, the way we made it back. We had an opportunity but this game is so fair sometimes. They deserve it. That’s all I can say.”

Like many in the arena, Nene was overcome with emotion with about four minutes left in the second quarter, when Webster made a baseline drive and had his shot blocked from behind by Spurs forward Kawhi Leonard. Webster fell to the ground and rolled into Duncan, whose back was turned to the action.

“Oh, that was scary,” Wittman said. “You never want to see that.”

Duncan eventually twisted and crumpled into a heap, unable to move as his teammates and Coach Gregg Popovich huddled around the player who led the franchise to four NBA championships and has kept it relevant for the past 16 seasons. Before going down, Duncan was once again methodically effective, scoring eight points with five rebounds in 13 minutes. Nene, who worked out with Duncan during the lockout nearly two years ago, said he told him, “No, no, no, no, no.”

Webster, who watched Duncan collapse in front of him took it even harder after Duncan walked off the court and headed to the locker room, never to return after spraining his already injured knee and suffering a sprained right ankle in the process.

“I lost my footing, right there in the air. That’s an unfortunate situation,” Webster said after scoring 14 points. “I was sad to see him go down. I would never wish that upon anybody, let alone fall on anybody like that. It was crazy it happened, but my prayers, my heart goes out to him that everything is okay and he has a speedy and healthy recovery.”

The Spurs didn’t appear to be immediately affected by losing Duncan, as they outscored the Wizards 13-1 and led, 51-24, before halftime. Tony Parker (19 points, 12 assists) pushed the lead back up to 27 with seven minutes remaining in the third quarter. But the Spurs were quickly undone by boredom or the loss of Duncan, as the Wizards staged an improbable second-half comeback.

A day after spraining his left shoulder in the second quarter of a loss in Memphis, John Wall didn’t appeared to be hampered by the injury as he scored 21 points with nine assists and five rebounds and led a unit that included Webster, reserves Kevin Seraphin and Trevor Ariza and seldom-used forward Chris Singleton on a 30-9 run that brought Washington within six points with 8 minutes 37 seconds left in the game.

“Everybody felt embarrassed to only have 26 points in the first half,” Wall said, when asked what sparked the turnaround. “We know they’re a team, nobody is going to lay down for you and we stepped it up and kept playing. That’s the way we’ve got to play the whole game. We’re not a team that can turn it on in the second half and try to get back on leads.”

Having seen enough, Popovich put starters Parker, Leonard, and Tiago Splitter, who made back-to-back layups to restore order as the Spurs (38-11) won their 10th in a row overall and 18th straight at home.

The Wizards (11-35) have now lost 13 consecutive games in San Antonio, a string of defeats that dates back to Dec. 11, 1999 — before any player on the current roster entered the league. They didn’t help their cause in the first half, scoring a season-low 26 points and shooting 26.2 percent from the field. They also set a season-low with nine points in the second quarter, creating a deficit so large that they scored 60 points in the second half and still lost by double digits.

“It was a nightmare,” said Nene, who scored 11 points, despite scoring scoring in the first half, missing all six of his field goal attempts and both free throws. “That thing happen sometimes. You know, nobody making shot and the more you try, the more you force, the more you look bad.”

Singleton had been stashed deep into the rotation in the past month, but Wittman decided to give an opportunity with the Wizards down by a bunch and he responded with 11 points.

Ariza added 10 off bench for the Wizards, who are now 3-21 away from Verizon Center and have lost four straight on the road.

“I mean the first half, we didn’t play together, with any enthusiasm,” Wittman said. “After having a little bit of success, we’ve crept in a little bit of minutes and shots and points. We addressed it. We played some different guys and we played with some enthusiasm and some heart. When we do that, we’re a pretty good team. That’s the team we were a couple of weeks ago.”