Sources - Grizzlies' Steven Adams (knee) likely to miss postseason

Memphis Grizzlies center Steven Adams is likely to miss the postseason with his injured right knee, sources told ESPN's Adrian Wojnarowski.

Adams, who underwent a stem cell injection about a month ago, has not played since spraining his posterior cruciate ligament while diving for a loose ball in the final seconds of a Jan. 22 loss to the Phoenix Suns.

Adams was originally expected to miss three to five weeks. He was ruled out for the rest of the regular season after receiving a stem cell injection in the knee on March 8.

Adams, 29, who agreed to a two-year, $25.2 million contract extension during training camp, averaged 8.6 points, 11.5 rebounds and 1.1 blocks in 42 games this season. The Grizzlies went 28-14 with Adams in the lineup.

Memphis will also be missing key reserve center Brandon Clarke (torn Achilles tendon) during the playoffs. Xavier Tillman Sr. has played capably as Adams' replacement, averaging 9.7 points and 6.7 rebounds in 29 starts.

The Grizzlies, the Western Conference's No. 2 seed, addressed their depth issues in the frontcourt by converting rookie power Kenneth Lofton Jr.'s two-way contract to a four-year, $7 million deal, his agents Mike George and Corey Barker of One Legacy Sports told ESPN. Lofton, the G League's Rookie of the Year, would not have been eligible for the playoff roster if he remained on a two-way contract.

The Grizzlies are waiving rookie point guard Kennedy Chandler, a second-round pick, to create a roster spot for Lofton.