LAS VEGAS — Even after an absence of nearly one month, Victor Wembanyama can enter a game cold, off the bench, and make a difference as large as his towering 7-foot-4 frame.

In his return from a calf strain, Wembanyama scored 15 points in the fourth quarter Saturday night, leading the San Antonio Spurs over the Oklahoma City Thunder 111-109 in the NBA Cup semifinals at T-Mobile Arena.

Playing on a minutes restriction, Wembanyama finished with 22 points, nine rebounds, two assists and two blocks, ending the Thunder’s 16-game winning streak and one of the best starts in NBA history. Oklahoma City dropped to 24-2.

The Spurs (18-7) advanced to the NBA Cup championship game Tuesday night against the New York Knicks (18-7). The Knicks defeated the Orlando Magic 132-120 in the earlier semifinal Saturday.

San Antonio outscored the Thunder by 21 points during Wembanyama’s 20 minutes, 39 seconds of playing time. In the other 27 minutes, 21 seconds, the Spurs were outscored by 19 points.

With San Antonio clinging to a 108-106 lead with 6.1 seconds remaining, Wembanyama made one of two free throws to extend the Spurs’ lead to three points.

Wembanyama was at his best during the fourth quarter, blocking a shot by Thunder big man Chet Holmgren, sinking a 12-foot jumper over Jalen Williams and hitting a short baseline jumper that extended San Antonio’s lead to 85-79.

Wembanyama made his return to the Spurs’ rotation as a reserve. The Spurs started center Luke Kornet, along with guards De’Aaron Fox and Stephon Castle and forwards Devin Vassell and Harrison Barnes.

San Antonio entered Saturday with a 3-0 record with that five-man lineup starting.

That success wasn’t duplicated to begin the game, with the Spurs trailing 14-4 before they made their first substitution.

And Wembanyama wasn’t even the Spurs’ first sub off the bench. (That was rookie guard Dylan Harper). Wembanyama did not play at all in the first quarter, with Oklahoma City leading 31-20 through the first 12 minutes.

Wembanyama started the second quarter with Fox, Harper, Julian Champagnie and Barnes. On his first two offensive possessions on the floor, Wembanyama collected offensive rebounds, finishing the first with a putback and the second by assisting a Harper 3.

Wembanyama’s first stint was very short, lasting only 3:23, but the Spurs outscored the Thunder by seven points in that time and forced a Thunder timeout after Wembanyama assisted on a Champagnie corner 3. Wembanyama added a steal and four rebounds in his first stint. Oklahoma City promptly went on an 8-0 run as soon as Wembanyama left the floor to reestablish a double-digit lead.

Wembanyama’s second shift began with 3:52 left in the first half and the Thunder leading 47-31, outscoring the Spurs by 23 points in Wembanyama’s time on the bench. This time, Wembanyama lined up with Vassell instead of Champagnie, along with Fox, Harper and Barnes. Wembanyama committed an offensive foul drawn by Shai Gilgeous-Alexander with 2:55 left, but the Thunder never scored the rest of the first half, with Wembanyama capping a 13-0 run with a 28-foot 3.

Wembanyama’s return felt like a long time coming, even though he was gone for only one month.

Wembanyama strained his left calf on Nov. 14 and missed San Antonio’s next 12 games.

The Spurs fell to 8-4 in the game in which Wembanyama suffered his calf injury.

But fortunately for San Antonio, some reinforcements were on the way. On Nov. 8, Fox made his regular-season debut, returning from a right hamstring strain that prevented him from playing in the team’s first eight games. Fox performed superbly during Wembanyama’s absence, averaging 25.2 points on 48 percent shooting from the field and 41 percent shooting from deep, and adding 6.5 assists per game.

With Fox leading the way, as well as contributions from up and down the roster, San Antonio posted a 9-3 record in the games that Wembanyama missed.

This story will be updated.