October 16, 2021 Borussia Dortmund's Erling Braut Haaland celebrates scoring their third goal with Jude Bellingham REUTERS

Borussia Dortmund top striker Erling Haaland scored twice on his return from injury with a second half penalty to help his team beat Mainz 05 3-1 on Saturday to go top of the Bundesliga table.

The Norwegian forward, who had been out since late September with a muscle injury, looked to be back at his very best and continued his sensational scoring run in the Bundesliga, having now netted 49 times in 49 league matches.

The 21-year-old opened his account on Saturday with a spot kick in the 54th minute following a lengthy VAR review over a hand ball and then struck again deep in second-half stoppage time.

Dortmund go top on 18 points, two ahead of champions Bayern Munich and Bayer Leverkusen, who face each other on Sunday. Freiburg are also on 16 points following their 1-1 against RB Leipzig.

"It is clear he had been missing in our team," Dortmund captain Marco Reus, who scored their opener, said of Haaland. "It is important that he plays because he constantly keeps two or three players occupied."

"To score two goals on his comeback is top. That is why we signed him."

The hosts, who travel to Ajax Amsterdam for the Champions League next week, had shot out of the blocks and earned a dream start with Reus thumping in a deflected cutback in the third minute for a dream start.

It was Reus' 14th goal in 20 games against Mainz, the most he has scored against any Bundesliga club.

In a tense first half Dortmund had three quarters of possession but had to wait almost the entire half for another chance in stoppage time, when a Jude Bellingham effort was cleared off the line.

Haaland's penalty gave Dortmund a measure of comfort in the second half and Mats Hummels hit the post with a glancing header but the visitors were not yet done.

Mainz struck with Jonathan Burkardt in the 87th from a mistake by Dortmund keeper Gregor Kobel to set up a nervous finale, before Haaland settled it in extra time to make it 70 goals in 68 matches in all competitions for his club, securing them their ninth consecutive home league win.