(AFP) - Pierre-Emerick Aubameyang has resumed his duel with Robert Lewandowski to be the Bundesliga's top scorer by netting twice in Borussia Dortmund's 2-1 win over Mainz on the opening weekend of the new season.

Aubameyang scored 25 German league goals last season, finishing second to Bayern Munich striker Lewandowski's 30 in the scorers' charts, and the duo look set to lead the way again in 2016-17.

Lewandowski scored a hat-trick in Bayern's 6-0 rout of Werder Bremen on Friday and his Dortmund rival Aubameyang opened his account less than 24 hours later.

The Gabon star headed in a 17th-minute opener and then added a late penalty before Japan striker Yoshinori Muto pulled one back at the death for the visitors.

Dortmund coach Thomas Tuchel was without Marco Reus, who was watching on in the stands as he recovers from a groin injury, but he started with three summer signings in his line-up.

He gave Bundesliga debuts to Spanish centre-back Marc Bartra, signed from Barcelona, and 19-year-old French winger Ousmane Dembele, brought in from Rennes, while ex-Bayern midfielder Sebastian Rode also started.

Aubameyang was unmarked at the far post to head in the opener from a cross from the left by Germany winger Andre Schuerrle.

He then doubled his tally on 89 minutes when Schuerrle was brought down in the area and the Gabon star converted the resulting penalty, before Muto set up a nervous ending with a header in the 92nd minute.

"As far as I know my team, I can only think that they wanted to show everything they can do, which made things a bit nervous and not too tidy in our structure and the way we found space," said Tuchel.

"Things were a bit tough, so it was a very laborious victory."