Gregg Popovich says that Kawhi Leonard's return this season is unlikely and that the team has to move on. (1:00)

After spending 10 days before the All-Star break in New York consulting with a specialist to gather a second opinion on his right quad injury, All-NBA forward Kawhi Leonard bears the burden of determining when he's prepared to play again, sources told ESPN.

Leonard has been medically cleared to return from the right quad tendinopathy injury, but since shutting down a nine-game return to the San Antonio Spurs that ended Jan. 13, he has elected against returning to the active roster, sources said. If Leonard returns, it will be because he has decided he can manage the discomfort of the injury, according to the sources.

Away from the Spurs to pursue second opinions in New York, Leonard recently utilized the gymnasium inside the National Basketball Players Association headquarters in Manhattan for workouts, league sources told ESPN. The Spurs had team personnel accompanying Leonard in New York, sources said.

Spurs coach Gregg Popovich told reporters Wednesday that he would be "surprised" if Leonard returns this season. Spurs officials are clearly starting to prepare his teammates for the possibility that they'll have to enter the playoffs without Leonard.

The hope of Leonard's return had buoyed the Spurs to believe they could still make a run in the Western Conference postseason. San Antonio is 35-24 and holding the third seed in the Western playoff chase.

The injury, rehabilitation and timetable for a return has complicated the Spurs' and Leonard's relationship, causing tension and fraying the fabric of what was once a strong partnership, league sources told ESPN. The uncertainty surrounding this season -- and Leonard's future, which could include free agency in the summer of 2019 -- has inspired a palpable stress around the organization, league sources said.

"We only have X number of games left in the season, and he's still not ready to go," Popovich told reporters in San Antonio on Wednesday. "If by some chance he is, it's gonna be pretty late into the season, and it's going to be a pretty tough decision -- how late to bring somebody back. So that's why I'm just trying to be honest and logical. I'll be surprised if he gets back this year."

Leonard, 26, has developed into one of the NBA's most dominant players and had been expected to be an MVP front-runner this season. He's a two-time first-team All-NBA selection and a two-time defensive player of the year, and he won the NBA Finals MVP in the 2014 championship series against the Miami Heat.