IRVINE, Calif. -- Two-time Super Bowl champion running back Sony Michel has decided to retire on the opening weekend of training camp with the Los Angeles Rams.

Coach Sean McVay announced Michel's decision on Saturday after the third practice of camp for the Rams, who re-signed Michel last month. McVay said they had a conversation that morning in which Michel informed the team of his intention.

Michel, 28, was entering his sixth NFL season after a four-year college career at Georgia. He won a Super Bowl ring in his rookie season with the New England Patriots, and he earned a second championship with the Rams three years later.

McVay called Michel "the epitome of a pro" and "a hugely instrumental piece" for the Rams' 2021 title team.

"What an incredible player. What a great career this guy has had," McVay said.

He added: "It's a bummer. His body's feeling like it's talking to him, and I have nothing but respect and appreciation for the competitor that he is and love Sony."

Michel spent last season as a backup with the Los Angeles Chargers before re-signing with the Rams. He was expected to be the primary backup to Cam Akers this season, but McVay said the Rams will now look to sign another veteran running back to join Akers and young players Kyren Williams and Zach Evans.

Rams star defensive tackle Aaron Donald said he did not know of Michel's decision to retire until he met with reporters after the training camp practice. Donald said he and the Rams are still getting used to many new faces in camp this season following a disappointing 5-12 season.

"Right now, we're just trying to get back on top," Donald said. "Obviously, we didn't have the season we wanted as a team last year. Now you are kind of looked over as a team so I feel like we got something to prove. So that is the motivation right there.

"We all need some type of fire, something to push you, something to get you going. And that is something that I am hanging on right now. I feel like we got something to prove as a team, I think I got something to prove as a player."

Michel was a first-round pick by the Patriots in 2018, and he scored the only touchdown in their 13-3 victory over the Rams in Super Bowl 53. He rushed for at least 900 yards in each of his first two seasons with New England, and he added 845 yards for the Rams in the 2021 regular season.

Michel rushed for 3,243 yards and 18 touchdowns in his five NFL seasons.

ESPN's Ohm Youngmisuk and The Associated Press contributed to this report.