DALLAS -- Holger Geschwindner, who has mentored Dirk Nowitzki since he was a teenager in Wurzburg, Germany, believes the 35-year-old Dallas Mavericks star can play at a high level for "three or four more years easily," barring serious injury.

Geschwindner has encouraged Nowitzki, who made his 12th All-Star appearance this season, to play long enough that he'll have no regrets after retiring.

The only players to average more points in a season than Dirk Nowitzki while playing most of their games at 35 or older: Kareem Abdul-Jabbar, Elgin Baylor, Alex English, Michael Jordan and Karl Malone. Kevin C. Cox/Getty Images

"Dirk is not living out of his physical abilities -- can [not] jump like crazy, run as quick as some -- so the thing is, on that level, I guess if he's not seriously injured he can play three or four more years easily," Geschwindner said Friday during an interview with ESPNDallas.com after the Mavs' practice. "The basic idea is as long as it's fun to go into work on the court and it's still interesting, he should do it, because I think the worst is if you stop and then you sit at home and think, 'Oh,' and you want to come back. You know all the big names that tried to do that. That does not work and it doesn't make sense.

"So play until you die and they drag you off the court. Then it's over. Then you really know it's over and you can live with it."

Nowitzki has publicly declared on several occasions that he intends to re-sign with Dallas at a significantly reduced salary after he becomes a free agent this summer. The 16-year veteran, who is projected to finish the season among the top 10 scorers in NBA history, has repeatedly said that his next contract will be for two or three years.

There were questions about how much longer Nowitzki, the 2007 league MVP and 2011 Finals MVP, could serve as a franchise centerpiece after he struggled with knee problems the past two seasons, undergoing arthroscopic surgery on his right knee that sidelined him for the first 27 games of the 2012-13 season. Nowitzki averaged 17.3 points per game last season for a 41-41 team that failed to make the playoffs, his lowest scoring average since 1999-2000, his second year in the NBA and the last time the Mavs didn't qualify for the postseason.

However, after an offseason of intense strength and conditioning work, Nowitzki has stayed healthy and produced at a historic level for a player his age. He's averaging 21.4 points for a 43-30 Dallas team that's fighting for a playoff spot. The only players in NBA history who averaged more points while playing the majority of games in a season at age 35 or older are Kareem Abdul-Jabbar, Elgin Baylor, Alex English, Michael Jordan and Karl Malone.

Geschwindner believes that even as Nowitzki's athleticism further decreases, the 7-footer can and should continue to be a major contributor for the Mavs.

"If you watch all the other big guys, like Marc Gasol and those guys, everybody is shooting out of standing," said Geschwindner, who arrived in Dallas from Germany on Tuesday to help Nowitzki snap out of a slump. "They do not shoot a jump shot. If Dirk's jump shot is gone, he still can do the shooting and standing, I believe. We will see.

"I guess the key is emotionally if you have fun doing it and you like to walk on the court and compete, do it. But don't sit at home watching TV and get crazy. Do what you would like to do."