Parsons originally planned to wait until Tuesday night to play, according to league sources, but he was declared ready after a phenomenal pregame workout Friday night.
"Felt great in workout. I'm ready to rock," Parsons told ESPN in a text message. "No reason to wait."
Memphis signed Parsons, widely considered the most high-profile free-agency addition in franchise history, to a four-year, $94 million maximum contract in July despite his previous two seasons ending prematurely with surgeries on his right knee. Concerns about the knee prompted the Dallas Mavericks to decline to make a serious bid to keep Parsons after he opted out of the final season of his contract last summer.
The Grizzlies exercised extreme caution, as Parsons recovered from arthroscopic surgery to repair a torn meniscus in the knee -- an operation he underwent in March -- less than a year after having a more complicated hybrid microfracture procedure on the knee. Parsons didn't begin full participation in Memphis' practices until the week before the regular season began and sat out the Grizzlies' first six games.
Parsons reported no problems with the knee since he started full-speed workouts, but conditioning is a concern after such a lengthy layoff and with little practice time to work his way back into shape.
The Grizzlies are off to a 3-3 start and need the scoring punch and playmaking the 6-foot-10 Parsons can provide. Memphis is averaging 95.0 points per 100 possessions, the league's fourth-worst offensive rating.
Parsons will likely start on a minutes restriction in the low 20s. He got off to a slow start last year when he dealt with strict minutes restrictions early in the season, but the Grizzlies gave him more time to work into a rhythm than he got a year ago, when he pleaded to play in the first week of the season.
Parsons played the best basketball of his career last season before reinjuring the knee, averaging 18.9 points, 5.9 rebounds and 3.2 assists per game while shooting 51.9 percent from the floor and 47.7 percent from 3-point range over a two-month span.