Blake Griffin’s quadriceps injury is improving but a return to Clippers could be weeks away

Blake Griffin continues to provide a lesson in the finicky nature of partially torn quadriceps tendons.

The Clippers’ All-Star forward is progressing in his recovery from the injury that has sidelined him since the day after Christmas, but there remains no definitive timetable for his return.

Griffin has started shooting free throws, is running on an anti-gravity treadmill and is expected to complete some weight-bearing activities in the next few days. His next doctor’s appointment is late next week, meaning he will likely miss more than another week.

“Things are going well,” Clippers Coach Doc Rivers said Friday. “I don’t know if that means in a week or three or four days. I don’t know. I can tell you most likely not.”

Once Griffin receives clearance to practice, he would probably need a few more days before playing in a game, meaning his return most likely will come during a five-game trip that starts Jan. 21 in Cleveland.

The Clippers have gone 6-0 in Griffin’s absence, continuing their remarkable ability to persevere in recent seasons without one of their top players. They went 12-6 during the 2013-14 season when point guard Chris Paul was sidelined by a shoulder injury and 9-6 last season when Griffin was out with a staph infection in his right elbow.

“You sort of have to come together in a hurry,” Paul said. “Different guys have to step up in different roles. When Blake comes back, I think it’ll give everybody a little more added confidence. Obviously, right now, J.J. [Redick] and myself, we’re shooting a lot more shots. That probably won’t be the case when Blake comes back. But, things come a lot easier when Blake plays.”

Paul said Griffin’s absence forces the Clippers to place more emphasis on defense because getting transition points becomes more important without him in the lineup.

“With Blake out there, our offense runs so much smoother,” Paul said. “Everything is so crisp. We know where everyone is going to be on the court.”

Unsung hero

Rivers said Luc Mbah a Moute’s value has increased with Griffin sidelined because the veteran forward has been defending power forwards in addition to small forwards and shooting guards.

Mbah a Moute was rewarded for his tenacity Thursday when his $1.3-million contract became guaranteed for the rest of the season. It might be one of the biggest bargains in the NBA.

“Luc is the most underappreciated person on our team, in all honesty,” Paul said. “He does everything. He defends. He cuts. He does everything a coach would appreciate but a fan has no idea that he’s doing.”

Etc.

Paul picked up a big All-Star endorsement from singer Justin Bieber, who asked his 73 million Twitter followers to retweet two requests to get the guard into the midseason showcase. As of Friday afternoon, the requests had been retweeted 65,000 times, which counted as that many votes because they included Paul’s name and the hashtag #NBAVote. Paul ranked third among Western Conference guards in the latest fan voting figures, more than 210,00 votes behind Oklahoma City’s Russell Westbrook for second place. The top two guards in voting will be the starters for the West in the All-Star game Feb. 14 in Toronto. . . . Forward Wesley Johnson did not practice because of plantar fasciitis in his right foot, an arrangement that Rivers said probably would continue even though Johnson has not missed a game because of his condition.

Up next for the Clippers:

vs. the Charlotte Hornets

When: 12:30 p.m Saturday.

Where: Staples Center.

On the air: TV: Prime; Radio: 980, 1330.

Records: Hornets 17-18, Clippers 23-13.

Record vs. Hornets: 1-0.

Update: Charlotte has lost five consecutive games since learning center Al Jefferson would be sidelined for six weeks because of a right knee injury, its slide starting with a 122-117 defeat against the Clippers on Dec. 30. It hasn’t helped that Nicolas Batum has missed three consecutive games because of a sprained toe on his right foot. Batum is listed as questionable to play Saturday.

ben.bolch@latimes.com

Twitter: @latbbolch