Fresh from scoring four goals in a 6-0 demolition of Union Berlin last time out, Guirassy put Dortmund in front five minutes into the second half, tapping in a Karim Adeyemi pass.

Adeyemi put Dortmund in the driver's seat with an excellent solo goal eight minutes later.

The 23-year-old Adeyemi, one of the smallest players on the pitch, latched onto a long ball and used his strength to grapple past two defenders before slotting home.

It is the first time Dortmund have won two in a row in the league this season.

Dortmund, who host Lille in the Champions League last 16 on Tuesday, sit 10th, six points off fourth with 10 games remaining.

Guirassy has 24 goals in all competitions for Dortmund since arriving from Stuttgart in July, more than St Pauli have managed in the league all season.

Leipzig let a one-goal lead slip to lose 2-1 at home against Mainz, who moved into fourth spot.

Xavi Simons gave Leipzig the best possible start, tapping in a rebound from close range after one minute.

Mainz turned the game in six second-half minutes.

One-time Germany midfielder Nadiem Amiri cut in from close range after 52 minutes and current national team striker Jonathan Burkhardt added a second six minutes later.

Mainz, who narrowly escaped relegation last season, are on track for a first-ever Champions League participation.

Leipzig have won just one of their past eight games in the league and are in danger of missing Champions League qualification for the first time since 2017-18.

Elsewhere, Wolfsburg kept their hopes of European qualification on track with a 2-1 win at Werder Bremen, thanks to a double from Patrick Wimmer.

Wolfsburg are seventh, one point and one place behind Leipzig, who occupy the final Europa League qualification spot.

A Robin Hack double and a Nathan Ngoumou goal took Borussia Moenchengladbach to a dominant 3-0 win at Heidenheim, drawing the Foals level with Wolfsburg on 37 points.

Heidenheim picked up a crucial win in their bid to avoid the drop, beating lowly Bochum 1-0 with Bayern Munich-bound Tom Bischof scoring the only goal.

Later on Saturday, defending champions Bayer Leverkusen play at Eintracht Frankfurt, hoping to cut the gap to league leaders Bayern, who beat Stuttgart away on Friday, back to eight points.

Leverkusen then face Bayern in their Champions League last 16 tie with the first match in Munich on Wednesday.