Mats Hummels scored goals in each half as Borussia Dortmund came back late to win 4-2 away at Freiburg on Saturday.

Hummels put Dortmund in front early but the side again suffered a collective blackout, allowing Freiburg to take the lead in first-half injury time with two quick goals.

Donyell Malen gave far too much space to Freiburg's free-kick specialist Vincenzo Grifo, who threaded a ball into the box, allowing Lucas Hoeler to head the home side level.

Just four minutes later, the Dortmund defence again lost track of a free kick, Nicolas Hoefler heading in to give his side the lead.

Malen equalised midway through the second half thanks to a clever assist from Germany striker Niclas Fuellkrug.

Dortmund looked set to drop points for the third straight game before Freiburg goalscorer Hoefler saw red with eight minutes remaining, giving the visitors a one-man advantage which they duly used.

Hummels scored again, trickling the ball into goal with two minutes remaining, before Marco Reus added a fourth to seal the win, giving the side a timely boost ahead of Tuesday's trip to Paris Saint-Germain.

Hummels praised his side for "winning ugly", saying "Freiburg at home is hard work".

The former captain however called on his teammates to improve.

"To have class and calmness on the ball... that's something we need to improve if we want to be a top team," he said.

Dortmund captain Emre Can called the win "stressful".

"It's not easy to win here in Freiburg and we did it today," said Can.

Hummels' goals meant the 2014 World Cup winner has now scored in 16 consecutive Bundesliga seasons.