Dirk Nowitzki is out for at least the next week, and possibly longer, though no official timetable has been set for his return. MRI tests confirmed a moderate left high ankle and mild left knee sprain for the reigning MVP.

“Every one of those types of injuries heals differently,” Avery Johnson said Monday after practice. “We’re just hoping that we catch a break and his heals pretty soon, but right now Dirk’s not coming back and that’s the way we’ve got to look at it. In the meantime we’ve got to have some really good efforts from the whole team.”

Nowitzki was injured in Sunday’s loss to San Antonio at the 3:19 mark of the third quarter. He had just blocked the shot of Ime Udoka before his left leg buckled under the Spurs forward. The seven-time All Star is currently walking in a protective boot without crutches.

“It was really an awkward and unfortunate play,” Nowitzki said. “My leg kind of got caught in the wrong place, so it’s just a little disappointing now, but the good thing is it could have been a lot worse. I was really lucky. Something more could have happened to my knee or my leg could have been broken, so I think this is the best-case scenario.”

Nowitzki is on pain killers and anti-inflammatory medication. He was up every two hours Sunday night icing the knee. Nowitzki has traditionally been a quick healer, but, as he freely admits, high ankle and knee sprains are uncharted territory.

“I don’t really have any experience with this,” he said. “This is fairly new to me, and with the knee, I never really had a knee problem or a sprained knee before. I’m just going to take it day-by-day. The first 48 hours are important.”

As for the timetable, Nowitzki echoed the team’s assessment: “I really don’t know how long it’s going to take. A week, two weeks, I really have no idea.”

The Mavs return to action Tuesday against the Clippers at home and only 12 games remain in the regular season, which ends April 16. The Mavs currently sit seventh in the Western Conference and have road games coming up at playoff contenders Denver (Thursday) and Golden State (Sunday).

“Looking at the tight playoff picture, every game hurts to sit out,” Nowitzki said. “This is probably the most painful time to miss games, so that’s very discouraging. Like I said, I’m trying to see a positive and it could have been a lot worse. It could have been a season-ending injury or even career-ending.”

Johnson is hopeful the team can rally around its fallen leader and get back on track. The Mavs (44-26) have dropped three straight and are currently tied with the Warriors in the loss column. Nowitzki has missed only one game this year, a 113-98 loss to Houston earlier this month.

“I’m hoping that we’ll do much better than we did when he got suspended,” Johnson said. “I think we were in a little fog against the Rockets, but now that we know that he’s not coming back right now, hopefully guys won’t look to the locker room.

“There’s no Dirk coming out of a phone booth or anything, so hopefully that will help us mentally prepare for these games.”

There’s more to replacing Nowitzki than just making up 23.8 points and 8.8 rebounds. The team has to close ranks and everyone needs to pick up the slack collectively. As far as the lineup goes at power forward, look for an increased role from Brandon Bass, Malik Allen and Devean George.

There’s also more heaped on the plate of veteran leaders such as Josh Howard, Jason Terry, Jason Kidd, Jerry Stackhouse and Erick Dampier. The Mavs know their postseason lives are on the line.

“Everybody has just got to pick up their game and we’re going to have to do it as a team,” Kidd said. “That’s the beauty of this right now, is that we show we’re confident and do it without Dirk until he gets back.”

Nowitzki talked about getting on the underwater treadmill the next few days, though he’s not sure if that’s a realistic possibility. He has complete trust in the team’s medical staff, adding that the doctors and trainers have his best interests at heart.

He’s not sure if he’ll be allowed to travel on the upcoming road trip and joked about sleeping in a hyperbaric chamber if it’ll help.

“I will do whatever they tell me,” Nowitzki said. “I’d love to go and support the troops and be there, but if it’s best to stay here and get treatment and sleep in whatever chamber I need to sleep in, I guess I’ll do that.”