Jupp Heynckes has come out of a four-year retirement to take charge of Bayern Munich for a fourth time, but opinions are divided as to whether the treble-winning coach can boost their flagging fortunes.

Chairman Karl-Heinz Rummenigge is convinced Bayern have the "ideal coach" for now in Heynckes, who will lead the team only until the end of the season -- he took over after Italian Carlo Ancelotti was sacked 10 days ago.

However, senior figures in German football are not so sure the 72-year-old Heynckes can turn things around, especially given the stars of his 2012/13 treble campaign like Arjen Robben, 33, and the injured Franck Ribery, 34, are themselves ageing.

"Experience is important, Jupp Heynckes and his coaches did everything right (in 2013)," ex-Germany coach Berti Vogts told German daily Bild.

"Unfortunately on the playing side, experience isn't everything, especially in attack.

"For the likes of Arjen Robben and Franck Ribery, it's not enough at the top level of international football.

"They don't go into the challenges like they used to, especially away from home."

Germany coach Joachim Loew was wary about Heynckes's prospects.

"On most levels, experience is worth it's weight in gold in football, but not on all counts," said Loew.

"It shouldn't be over-emphasised in a team. You also need to keep things fresh and dynamic to be competitive at the top."

Having dominated the Bundesliga for the last five seasons, Bayern have shown signs of weakness this time around.

Ancelotti was sacked following a run of three games without a win, including the 3-0 Champions League debacle against Paris Saint-Germain.

Either side of that thrashing, Bayern twice threw away a 2-0 Bundesliga lead to draw against Hertha Berlin and Wolfsburg.

That has left them five points behind Borussia Dortmund -- the last team to deny Bayern the title in 2012 -- in the Bundesliga and prompted the Bayern board to act.

Following four-and-a-half years of retirement, Heynckes has returned for a fourth spell -- he coached Bayern from 1987 to 1991, briefly in 2009 as caretaker and then again between 2011 and 2013 -- in a bid to recapture the glory of the 2012/13 campaign when they won the Bundesliga, German Cup and Champions League, the only German club to achieve that feat.

"Heynckes and his two assistants are an established team and in these shaky times in which we find ourselves, they are some continuity which gives us security," said Bayern's Germany star Thomas Mueller.

However, Heynckes admits football has changed hugely since he last coached.

It's not just Heynckes rolling back the years, alongside his two assistants Hermann Gerland, 63, and Peter Hermann, 65, the Bayern coaching staff have a combined age of more than 200.

- Disgruntled squad --

Their first task will be to pull together a squad that showed signs of disgruntlement during Ancelotti's reign after senior players Mueller, Ribery, Robben and Robert Lewandowski all grumbled publically.

Magazine Kicker claimed Robben moaned that his 12-year-old son, playing youth-team football in Munich, had harder training sessions than Bayern's senior squad under Ancelotti.

Heynckes will also need to settle on a tactical formation after Ancelotti fluctuated between 4-3-3 and 4-2-3-1.

Ancelotti never figured out where best to play Mueller -- a favourite amongst Bayern's fans -- while his baffling decision to leave out Ribery, Robben, Mats Hummels and Jerome Boateng for the drubbing in Paris was surely one of the final nails in his Bavarian coaching coffin.

Tactically, Heynckes is expected to revert to the 4-2-3-1 formation with which Bayern won the 2013 Champions League.

With their lofty standards, Bayern's recent results have been unacceptable, and he'll be expected to change that, and fast.

And he'll have to do so with Ribery (torn knee ligament) and captain and goalkeeper Manuel Neuer (fractured foot) on the long-term injury list.

It will be a tall order and the challenges will come thick and fast, starting with Saturday's tricky trip to Freiburg followed by the Champions League visit of Celtic -- but Munich expects.