Knicks guard Quentin Grimes is mourning the loss of his former University of Houston teammate Reggie Chaney, who died at the age of 23 on Monday.

Chaney’s cause of death was not immediately known, according to multiple reports.

“Man I can’t believe this!” Grimes wrote on his Instagram Story, including a photo of him and Chaney during their playing days with Houston. “#RIPREGGIE.”

Grimes and Chaney were part of the Cougars team that helped Houston reach the Final Four in 2021 — its first trip to the final weekend since 1984.

A University of Houston spokesperson confirmed Chaney’s passing to ABC13 in Houston on Tuesday.

“Reggie was a beloved member of our program, appearing in more than 100 games from 2020-21 through the 2022-23 season,” the university said.

The school did not disclose further information about Chaney’s death.

Chaney had been set to join the AE Psychiko — a professional basketball team in Greece — according to the Houston Chronicle.

The Tulsa, Okla. native played two seasons for the Arkansas Razorbacks before transferring to the University of Houston, where he played three seasons. 

Chaney was named the American Athletic Conference’s Sixth Man of the Year this past season.

He played in 35 games with one start in his super senior campaign, averaging 3.0 points, 2.7 rebounds and 0.7 steals per game.

Chaney, who majored in liberal studies, graduated in May 2023.