Union Berlin’s Jordan Pefok thundered in an 84th-minute goal to secure a 2-1 home victory over Mainz on Saturday and send them top of the Bundesliga with a fourth straight league win. Union move to 39 points from 19 games, two ahead of Bayern Munich who visit VfL Wolfsburg on Sunday. Third-placed Borussia Dortmund are also on 37 points after thrashing Freiburg 5-1. Union, unbeaten at home this season, have now recorded two more league victories than Bayern. The hosts got off to a strong start with Jérôme Roussillon and Rani Khedira coming close before Kevin Behrens slotted in after 32 minutes for a deserved lead. Mainz had few chances in the game but they did get a 78th-minute penalty for handball thanks to a VAR review and substitute Marcus Ingvartsen equalised from the spot. It then took Union six minutes to carve out the winner, with Jordan rifling in from close range after Mainz failed to clear a cross, to keep their sensational campaign going. Borussia Dortmund crushed 10-man Freiburg, with Sébastien Haller on target for the first time since his return from cancer treatment, to the delight of the home fans. The visitors, who dropped to sixth place on 34 points, slipped up at the start with Kiliann Sildillia booked twice in three minutes to reduce his team to 10 men in the 17th minute. It did not take long for Dortmund to make their advantage count and former Freiburg defender Nico Schlotterbeck rifled in for the lead from the tightest of angles in the 26th. Dortmund had Freiburg firmly on the back foot but the visitors struck against the run of play with Lucas Höler drilling in a loose ball after the hosts had failed to clear it near the end of the first half. Order was quickly restored after the restart however as Dortmund scored twice in a span of three minutes. Jude Bellingham set up Karim Adeyemi with a backheel and the Germany international slipped the ball past keeper Mark Flekken to put Dortmund back in front. It was then Haller, back this year after undergoing surgeries and treatment for testicular cancer diagnosed only weeks after he had signed for the club last July, who scored his first competitive goal for them, heading in a cross in the 51st minute. Dortmund captain Marco Reus should have scored as well when he was left unmarked in front of goal at the far post, but he rattled the crossbar with his shot. Julian Brandt did not miss with a long-range effort that went in off the post and Gio Reyna completed Freiburg’s demolition in the 82nd minute, after Freiburg coach Christian Streich was sent off for dissent. Bayern visit Wolfsburg on Sunday when the 10-time defending champions can reclaim top spot. Eintracht Frankfurt defeated Hertha Berlin 3-0, Cologne drew with Leipzig 0-0, and Bochum outclassed Hoffenheim 5-2. In the late kick-off, bottom club Schalke held on for a point with a hard-fought 0-0 at Borussia Mönchengladbach. Andy Brassell is away – his Monday Bundesliga blog will return on 13 February