Leonard, who was already ruled out of Tuesday night's game against the Orlando Magic at AT&T Center, will also sit out Thursday's home contest against the New Orleans Pelicans, per Ramona Shelburne of ESPN.com. He is reportedly feeling "much better" but is not comfortable enough on his injured quadriceps to return to the floor.
Spurs coach Gregg Popovich says Leonard "has to be cleared by his medical staff" and is "frustrated" by the process, per Jeff McDonald of the San Antonio Express-News.
The Spurs remain hopeful their All-Star forward will be back at some point before the end of the 2017-18 regular season.
Leonard, 26, has played in just nine games all season because of his right quad injury. He averaged 16.2 points and 4.7 rebounds per contest, massive drops from his 2016-17 numbers as he struggled with discomfort.
Last week, Leonard told reporters he hoped to return to the lineup "soon" but did not give a specific timetable.
"I don't have a set date right now [for my return]," Leonard said, per Michael C. Wright of ESPN.com. "The progress I've been making has been great. [The pain] is diminishing. It's hard to explain, but I'm definitely better. I feel better, and I'm feeling more comfortable."
The Spurs have fallen into 10th place in the Western Conference, losing eight of their last 10 games and three straight. They are in danger of missing the playoffs for the first time since 1996-97. Leonard said he would return at some point this season if he feels comfortable.
"We've taken the right steps," Leonard said. "We don't want to take any steps back and just aggravate things. Like I said: It's hard to explain. But obviously, I'm a competitor, and if I can play, I'm going to go out and play like I did in the nine games, just to test it out. It just wasn't where we wanted it to be."
There aren't many incentives for Leonard to return this season. The Spurs have next to no hope of unseating the Houston Rockets or Golden State Warriors in the playoffs, even with a fully healthy Leonard. Holding him out would probably result in San Antonio winding up with the 13th pick in June's NBA draft, as well as a chance at landing a young player to potentially pair with the 2014 Finals MVP.