Jeff Green huge dunk on Ian Mahinmi

In what figured to be a waste of a preseason game with the Cavs holding nine of their 20 players out of the lineup — including their entire starting lineup — for either rest or rehabilitation, Green turned in a performance worth tuning in to.

Five of his eight field goals were dunks — including the one he yolked on Mahinmi — and he also contributed a chase-down block on Kelly Oubre Jr., with the 31-year-old Green looking every bit as athletic as the 21-year-old Wizards forward.

They almost had to stop the game at Capital One Arena after this Jeff Green dunk.

Lue coached Green as an assistant coach in Boston under Doc Rivers.

With their bond established, Lue called up Green this past summer with an offer to join Cleveland to play backup minutes behind LeBron James and Kevin Love.

Green made $15 million for the Orlando Magic last year but put up career lows across the board — 9.1 points on 39.4 percent shooting overall, 27.5 percent from 3 and 3.1 rebounds per game.

Lue offers praise for Green the person, as much as he does for Green the player — a 6-foot-9, 235-pound swingman with perhaps the most chiseled body on the Cavs, James included.

Green will be a part of what’s considered the deepest Cavs bench since James returned to Cleveland in 2014.

Green knows he is coming off the worst season of his career and is only a few years removed from missing the entire 2011-12 season after undergoing heart surgery at the Cleveland Clinic to repair an aortic root aneurysm.

“Everybody has their opinions of what Jeff Green should be or what I can do, but I have to go out there and prove it to myself that I work hard and I put in the work to be in the position I’m in.