New signing Paco Alcacer came off the bench to score two late goals and seal Borussia Dortmund's stunning 4-2 win as they fought back from two goals down at Bayer Leverkusen on Saturday to knock Bayern Munich from top spot in the Bundesliga.

Alcacer, on loan from Barcelona until June, came on after 63 minutes with his team 2-0 down, but tucked away goals on 85 and 94 minutes to cap the fight back after Dortmund had drawn level.

After Bayern crashed to a shock 2-0 defeat at Hertha Berlin on Friday, Dortmund left it late to top the table in dramatic style and build on their 7-0 rout of Nuremberg on Wednesday.

Leverkusen went ahead at their BayArena after just nine minutes when midfielder Mitchell Weiser hit the net with a spectacular shot from outside the area -- reminiscent of Benjamin Pavard's goal of the 2018 World Cup for France.

Burly defender Jonathan Tah doubled Leverkusen's lead by tapping home six minutes from the break.

Dortmund drew level with two goals in four minutes.

Danish midfielder Jacob Bruun Larsen, 20, drilled home the first on 64 minutes.

England junior international Jadon Sancho came off the Dortmund bench and a minute later provided the final pass for Dortmund captain Marco Reus to smash home a second on 68 minutes.

Dortmund went ahead for the first time on 85 minutes when Alcacer lunged to guide a cross by defender Achraf Hakimi, on loan from Real Madrid, into the Leverkusen net.

Alcacer completed the Roy of the Rovers-style finish on 94 minutes.

He tapped into an empty net after Dortmund attacked from their own box with Leverkusen goalkeeper Lukas Hradecky well out of his own penalty area as the hosts pushed for an unlikely late equaliser.

Dortmund are the only unbeaten team in Germany's top flight after Werder Bremen earlier blew the chance to knock Bayern from top spot by losing 2-1 at Stuttgart, even though the host's goalkeeper Ron-Robert Zieler conceded a howler of an own goal.

Bremen made a bad start when Greece striker Anastasios Donis dribbled through the visitors' defence and chipped into an open net on 19 minutes.

Then Bremen had key defender Milos Veljkovic sent off eight minutes from half time for pulling back Daniel Didavi, his second foul on the Stuttgart striker.

But then Zieler's blunder gave Werder an equaliser.

The 29-year-old, a 2014 World Cup winner, took his eye off the ball when defender Borna Sosa aimed a throw-in his way and, after he got a faint touch, watched in horror as the ball rolled into his net on 68 minutes.

Gonzalo Castro restored Stuttgart's lead 15 minutes from time.

Bremen had chances as midfielder Maximilian Eggestein and veteran striker Claudio Pizarro, who turns 40 on Wednesday and made his 450th Bundesliga appearance, hit the post.

Elsewhere, Julian Nagelsmann's Hoffenheim, who host Manchester City in the Champions League on Tuesday, suffered a 2-1 home defeat to RB Leipzig, who Nagelsmann will coach next season.

Denmark forward Yussuf Poulsen scored both of Leipzig's goals before Andrej Kramaric netted a late Hoffenheim penalty.

Borussia Moenchengladbach went fourth despite being held to a 2-2 draw at Wolfsburg, where they have not won for 15 years, as goals by Gladbach's Alassane Plea and Thorgan Hazard were cancelled out by Wolfsburg's Renato Steffen and Wout Weghorst.

Schalke, last season's runners up, climbed off the bottom of the table with a 1-0 win at Mainz when Austria midfielder Alessandro Schoepf headed the only goal after only 11 minutes.

The home win eases the pressure on head coach Domenico Tedesco as Schalke ended their run of five straight defeats to lift them to 17th, but they can drop down again if Hanover win at Eintracht Frankfurt on Sunday.

Nuremberg won the battle of the teams promoted last season when they romped to a 3-0 win over Fortuna Duesseldorf thanks to goals by Hanno Behrens, Mikael Ishak and Federico Palacios.