ISTANBUL - Pierre-Emerick Aubameyang scored twice as Borussia Dortmund exploited poor defending to beat Galatasaray 4-0 in the Champions League on Wednesday.

Dortmund's third victory in three matches strengthened its grip on Group D with nine points. Arsenal beat Anderlecht 2-1 and is second with six. Anderlecht and Galatasaray have one each.

Dortmund is struggling badly in the Bundesliga and is one point away from the relegation zone. But the last time Dortmund began the Champions League campaign with three straight wins was in 1997 when it won the title.

Aubameyang opened the scoring in the sixth minute, when he tapped in a cross from Marco Reus, and doubled the lead in the 18th with another simple strike from close range. Reus scored the third in the 41st by curling in a spectacular shot from more than 20 metres (yards).

Adrian Ramos added the fourth in the 83rd, one minute after coming on for Shinji Kagawa, who had set up Reus.

All four goals came after woeful defending by Galatasaray.

"We were very efficient," Dortmund's captain Mats Hummels said. "We had two early chances and we scored from both of them, and then of course it's easier to play. We also wanted to play good defence and we did."

Aubameyang was left with a simple tap-in on the first goal when Reus had plenty of space to cross. On the second, Henrikh Mkhitaryan sent Lukasz Piszczek racing and the defender had plenty of time to find Aubameyang.

Neven Subotic made a big clearance in front of Burak Yilmaz, then Aubameyang hit the post from close range from another Mkhitaryan pass.

Reus was left unchallenged when he fired his goal and Ramos also had plenty of space to place his shot after a good through ball from Ilkay Gundogan, another substitute who is coming back after missing 14 months with a back injury.