Three weeks ago, Williams Arena fans thought they’d witnessed the end of Oto Osenieks’ career.

Hampered by knee injuries, the junior power forward had announced he would hang up his sneakers, ending his career in maroon and gold as a student manager rather than a player.

Tuesday, it was that future retiree — who hadn’t played since that day — who helped bring new life into Minnesota’s present.

With center Elliott Eliason sidelined because of a left ankle injury and forward Joey King in early foul trouble, Osenieks made a surprising contribution, scrapping out a 32-minute, four-point, four-rebound night against one of the largest frontcourts in the nation.

Along with the hot-shooting guard trio of Andre Hollins (13 points), Austin Hollins (17) and DeAndre Mathieu (17), it was enough to nudge the Gophers past Florida State 67-64 in one nerve-racking overtime.

For the second time in three years, Minnesota will head to the NIT championship. The Gophers (24-13) will play SMU (27-9) at 6 p.m. Central time Thursday.

The 24 victories broke Minnesota’s school record.

“He came to us and said, “I want to play, I want to help this team,’ when Elliott went down,” Pitino said of Osenieks. “And you talk about the player of the game, it’s got to be him.”

The towering frontcourt of Florida State (22-14), including 7-1 Michael Ojo and 7-3 Boris Bojanovsky — was never able to capitalize on its huge size, as those two combined for eight points and eight rebounds in an overall poor shooting night for the Seminoles. But they found one final push at the end of regulation.

Minnesota was clinging to a 60-55 lead with 19 seconds left after Andre Hollins and Mathieu each hit a pair of free throws. But after Devon Bookert’s layup, Smith ricocheted two foul shots off the rim to set up a final chance for Florida State with 8 seconds to go.

With precious seconds ticking away, Bookert got the ball again and scooted up the court with Smith on him like a glove.

At the top of the arc, he separated enough to send a three-pointer sailing past Smith’s outstretched hand and through the net with 0.3 seconds remaining — 60-60 and overtime.

“Once it went up, you couldn’t do anything about it,” Austin Hollins said. “In that situation, you’ve just got to let it go and move on, and that’s what we did.”

Between the two teams, only 11 labored points were scored in the extra session. Both Florida State and Minnesota were clearly fatigued and sloppy. Thankfully for the Gophers, they owned seven of those points.