BOULDER - Twice in a span of six days, Cheyenne Mountain found itself in a roller coaster of a playoff game with the entire season riding on each and every possession.

This time, the Indians couldn't pull it out.

"That's basketball," Cheyenne Mountain forward Reece Eddy said.

Tyron Purifoy scored a game-high 33 points, Ibrahim Sylla scored nine of his 17 points in overtime and Denver South outlasted Cheyenne Mountain 79-75 Friday in a 4A boys' semifinal at the Coors Events Center.

"I realized that this is it," said Purifoy, a senior guard. "Either I step up or someone else steps up, but in the end, we're all a family. It didn't matter how we did it, as long as we got it done."

The Indians (21-6), who trailed by 13 late in the first half, hit their stride in a 22-point third quarter. With 1:13 left, Christian Nehme's shot from the lane highlighted a 12-0 run and gave Cheyenne Mountain a 52-45 lead.

South (19-8) caught up, pulling ahead on a Purifoy 3-pointer with 2:40 left in regulation that made it a 59-58 Rebels lead, then another Nehme drive put the Indians ahead, 60-59.

Again, Purifoy put South in front, this time converting a rebound off his missed free throw into a 61-60 lead. The Rebels led 64-62 until Nehme tied the game with 25.5 seconds left.

South missed seven free throws in the fourth quarter, and when Sylla's attempted tip-in as the clock wound down rolled off the rim, the Indians seemingly had new life as the game went into a fifth quarter.

That's when Sylla, in foul trouble for most of the game and having scored only eight points in regulation, really woke up. From the overtime tip, the 6-foot-8 senior got loose underneath, scoring six points, two on monster dunks, the last expanding the South lead to 72-68 with 2:32 left.

Ghassan Nehme, who scored a team-high 28 points, hit his only 3-pointer of the night with 19.8 seconds left to cut the Rebels lead to 78-75 and got another chance after a pair of Sylla missed free throws on the ensuing possession.

Six days after his incredulous four-point play won the game in double overtime against Thompson Valley, his potential game-tying shot from the right side hit the back of the rim, and South moved one step closer to its first state title in 44 years.

"It just didn't come out in our favor tonight," Ghassan Nehme said. "It was a heck of a game, a dogfight, just like last week (against Thompson Valley). They pulled this one out. It came down to whoever wanted it and who had the ball last at the end of the game."