By Oliver Trust

BERLIN, Dec. 21 (Xinhua) -- Jupp Heynckes is often described as a caring father for his players, especially the inexperienced and younger ones. And the way the 72-year-old is dealing with Arjen Robben and Franck Ribery proves the Bayern Munich coach is also an excellent help for the olders.

At present, Bayern fans can't imagine their team without Robben and Ribery. But time will come when the two superstars reach their limits, with the only question of when?

Heynckes has declined to stay for the next season despite a Bayern offer, and the future of Robben and Ribery is nothing he has to make up his mind about.

And a new coach, taking over in summer 2018, will have to decide about their future in collaboration with the club president Uli Hoeness and head of board Karl-Heinz Rummenigge.

Robben turns 34 in January and Ribery 35 next April. French Ribery joined the club over 10 years ago in 2007, Dutch Robben is wearing Bayern shirt for eight years after coming from Real Madrid in 2009. Both stand for a successful era containing several national and international titles.

Heynckes is treating the 2013 Champions League winners according to their age. After injuries, the 2013 treble winner is preventing them from reporting for duty too early, as he is convinced, without Robben and Ribery, Bayern won't be among the clubs battling for the 2017/2018 Champions League title.

"Arjen and Franck are essential for the team as they can rely on a lot of experience and quality. We know we need their quality to be successful not only in the Bundesliga but much more in the Champions League," said the 1974 world champion.

When Bayern beat 2013 Champions League finalist Borussia Dortmund in the last-16-round of the German Cup (2-1) Wednesday evening, Ribery was substituted after 60 minutes. Heynckes took it for safety reasons "as we had to go through many hard games and Franck is not one of our youngest ones, and he is working extremely hard."

And Robben was watching the game from the stands despite attending full training action after an injury break. "We didn't want to take any risk. We need a healthy Robben in 2018, so why do this game?" said Heynckes.

Neither Robben nor Ribery was happy about their coach's decision, but both accepted his explanations.

And their future remains a tricky topic as neither said of an early retirement. Rummenigge declined any negotiation regarding their future until spring 2018 as the club is aware of their current value.

He confirmed that Bayern is going to take up serious talks, "but there is no need to hurry."