Thomas Tuchel is looking to break Borussia Dortmund's winless streak at former club Mainz on Friday while runaway league leaders Bayern Munich aim to send more Bundesliga goal records tumbling in Bremen.

Bayern's 5-1 drubbing of Dortmund in Munich a fortnight ago opened an ominous seven-point lead at the top of the table as Pep Guardiola's side look to win a fourth straight league title this season.

Under new coach Tuchel, Dortmund won their first 11 games in all competitions, including five league victories to top the table, but consecutive draws to Hoffenheim and Darmstadt saw them throw away four points and drop to second before the Munich mauling.

Borussia are winless in their last four games and need to beat mid-table Mainz to maintain their second place, with arch rivals Schalke just a point behind.

Dortmund have won nine of their 18 meetings against Mainz and enjoyed a 4-2 win at home in February as Tuchel takes his team to the Coface Arena for the first time since quitting at the end of the 2013/14 season.

Gabon winger Pierre-Emerick Aubamenyang will be out to extend his phenomenal league record run of having scored in all eight league games so far this season.

Bayern head to Bremen's Weserstadion on Saturday looking for their 12th straight win this season having won 4-0 and 7-0 on their last two visits.

The Bavarian giants have won all of the last nine games against Werder with 39 goals scored and just six conceded.

Bremen have lost their last four games while Bayern are in goal-scoring form as Robert Lewandowski has netted 12 times in seven games and Thomas Mueller has scored eight goals in as many leagues games.

The pair have scored 20 of Bayern's 28 goals so far and Mueller says the league record of 101 goals scored by Munich legends Gerd Mueller, Uli Hoeness and Co. back in the 1971/72 season could be under threat.

"It is theoretically possible, that we could score over a 100 goals with this team," Mueller told Munich-based newspaper TZ.

"We won't be defined by it and we're not going out just focused on scoring goals, but we have fun playing football and are keen on success."

Bayern are set to be without winger Kingsley Coman after the France Under-21 winger returned from international duty with a thigh strain.

Guardiola is set to welcome back defender Holger Badstuber and winger Arjen Robben, who have both returned to training after lengthy injury lay-offs.

"This season is the best we have played since Pep Guardiola arrived," said midfielder Javi Martinez.

"We're playing unbelievably well, we are solid in every aspect, but we have to continue like that.

"We have to do exactly the same in the remaining matches.

"It won't bring us anything if we're good now and then let it go late in the season."

There will be an interesting battle to stay up near the top of the table on Saturday when Schalke, in third, host fourth-placed Hertha Berlin who are unbeaten in their last three games and just two points behind their rivals.

Schalke won six games on the trot before crashing to a 3-0 defeat last time out while Hertha romped to a 3-0 win at home to Hamburg as striker Vedad Ibisevic netted twice to leave him with four goals in five games this season.

Fixtures (all times 1330 GMT unless stated)