ANAHEIM -- Left fielder Justin Upton, who underwent an MRI exam on his right knee on Wednesday, will miss the rest of the season with patellar tendinitis, Angels manager Brad Ausmus announced after Friday’s 11-4 loss to the Rays.

Upton started to feel the injury last weekend while playing the White Sox in Chicago, and said earlier this week it’s similar to the issue that kept him out of action for most of Spring Training. Meeting with the medical staff after Friday’s game, it was determined that Upton will receive a platelet-rich plasma (PRP) injection and will be cleared for workouts in six weeks.

“He can begin load-bearing exercises and working out, which is a plus, because it’s something he didn’t get to do last year,” Ausmus said. “Those knee issues crept all the way into January. Hopefully it gets done early. A little over six weeks from now, he can start getting his offseason program in and be ready to go for Spring Training. The big thing is he can get a full offseason of training and be full go when we get to Tempe in 2020. That’s the important part.”

Upton, 32, didn’t make his season debut until June 17 after dealing with turf toe sustained in an exhibition game against the Dodgers just four days before the start of the regular season. He finishes the season with a .215/.309/.416 slash line with 12 homers, eight doubles and 40 RBIs in 63 games.

"In a sense, it’s been a lost season from an injury perspective," Ausmus said. "Never really got rolling, and then another injury. I think he’s really looking forward to an offseason where he can get going.”

Upton, signed to a five-year deal worth $106 million before 2018, still has three years and $72 million left on his contract. Ausmus, though, still believes Upton can offer plenty of offensive production when healthy.

“He’s still a big offensive threat,” Ausmus said. “It might take more work from a defensive perspective, just because of the knee issues and the toe issue. If he’s having a normal Upton season, and he’s there for the whole six months of the season, that’s a huge difference offensively.”