Thomas Mueller should return to action for Bayern Munich against Augsburg this weekend after three weeks on the treatment table.

Bayern will look to extend its perfect run under Jupp Heynckes on Saturday. The champion has won seven games out of seven since Heynckes took the reins last month. Having trailed Borussia Dortmund by five points at the beginning of October, Bayern now has a four-point lead at the top of the  Bundesliga .

Dortmund, meanwhile, will be without Pierre-Emerick Aubameyang as it looks to revive its title bid. Here are five things to look out for in this  Bundesliga  weekend:

Bayern stars return to squad

There was good news for injury plagued Bayern Munich this week, as Thomas Mueller, Jerome Boateng and Franck Ribery all returned to team training. None of the three are expected to start against Augsburg on Saturday. While Mueller and Boateng are set to return to the bench, Ribery is unlikely to be named in the squad after six weeks out with a knee injury. 

Augsburg has won just one of its last five games, and will be hoping that the return of Alfred Finnbogason can help them return to form in time to face a rampant Bayern outfit.

Aubameyang absent

Star striker Pierre-Emerick Aubameyang will be left out of Borussia Dortmund's squad for Friday's visit to Stuttgart.

Both Aubameyang and his team are currently in a miserable run of form. The striker has not scored, and Dortmund has not won, in any of his last five appearances.

"He has been scoring a lot of goals, but unfortunately only in training," joked coach Peter Bosz. On Thursday, Dortmund confirmed that Aubameyang would not travel to Stuttgart, in what Kicker magazine reported to be a "disciplinary measure". Bosz himself is under pressure, and nothing less than a win will do when Dortmund travels to Stuttgart.

"There is always pressure when you are not winning," said Bosz. "The challenge is turning things around again, and we will do that."

Schalke missing midfield stars

With Dortmund struggling, fourth-placed Schalke have a chance to overtake its old rival when it hosts Hamburg on Sunday.

Unbeaten in its last five games, Schalke will be without the injured Nabil Bentaleb, while midfield star Leon Goretzka is also a doubt after a recent bone problem. "We hope that (Goretzka) is able to play against Hamburg," said coach Domenico Tedesco, "but we will not take any unnecessary risks."

Hamburg, meanwhile, is expected to give a second  Bundesliga  start to 17-year-old Jann Fiete-Arp.

Leipzig welcomes back World Cup heroes

Attention turns back to the  Bundesliga  title race after a highly successful international break for RB Leipzig's stars. Striker Timo Werner got on the scoresheet for Germany against France, while Marcel Halstenberg made his international debut against England. Yussuf Poulsen and Emil Forsberg, meanwhile, celebrated World Cup qualification with Denmark and Sweden.

All four players will be in the starting eleven when Leipzig travels to Bayer Leverkusen on Saturday, as it looks to emulate last season’s 3-2 victory at the BayArena.

Four points behind Bayern in second place, RB may need a repeat performance to keep their title hopes alive.

Friends reunited in Bremen

Hanover’s visit to Werder Bremen on Sunday will pit old friends Martin Harnik and Max Kruse against each other.

The two strikers played together for 11 years at youth level, and will be on opposite sides of a crucial northern derby on Sunday. Bremen’s Kruse cannot afford to be friendly, however, with his side five points adrift of safety and desperately in need of a first season victory.

"There is a lot at stake for Bremen and for us," Harnik told Bild. "On the pitch, there will be more important things than our friendship."

Fixtures (all times GMT): Friday: VfB Stuttgart v Borussia Dortmund (1930)

Saturday: Bayern Munich v Augsburg, Hoffenheim v Eintracht Frankfurt, Bayer Leverkusen v RB Leipzig, Mainz v Cologne, Wolfsburg v Freiburg (all 1430), Hertha Berlin v Borussia Moenchengladbach (1730)

Sunday: Schalke v Hamburg (1430), Werder Bremen v Hanover 96 (1700)