Borussia Dortmund blew the Bundesliga title race wide open with a 4-1 win over Hertha Berlin on Sunday, but in-form striker Karim Adeyemi limped off clutching his hamstring in the first half.
Union's win sees them sit an unlikely second on goal difference behind the league leaders, while deepening the woes of Hertha.
Two goals in one first-half minute from striker Eric Maxim Choupo-Moting carried Bayern Munich to a narrow 3-2 victory away at Hertha Berlin in the Bundesliga on Saturday
French striker Anthony Modeste thanked Dortmund manager Edin Terzic after his first-half goal gave his side a narrow 1-0 win away at Hertha Berlin on Saturday
Bundesliga: Marco Richter scored twice as hosts Hertha Berlin earned a shock 3-2 win over second-placed Borussia Dortmund Saturday to leave Bayern Munich nine points clear at the top of the Bundesliga.
Atletico Madrid have signed Brazil striker Matheus Cunha on a five-year-deal from Bundesliga club Hertha Berlin.
Hertha Berlin's Sami Khedira, who won the World Cup with Germany in 2014, announced that he will retire from football at the end of the season.
Hertha registered a convincing 4-0 win over Union in the Berlin derby to move up to 10th place in the Bundesliga table.
Dedryck Boyata apologised for grabbing teammate Marko Grujic by the face, but said it was not a kiss or a celebration and that he was just giving instructions.
Bundesliga: Hertha Berlin defender Dedryck Boyata broke social distancing norms by kissing team-mate Marko Grujic on the cheek to celebrate a goal.
Niko Kovac suffered his first defeat in nine games as Bayern's head coach.
Thomas Muller returned to team training on Monday and hoped to start against Hertha Berlin after being sidelined by a virus from Bayern Munich's win over Ingolstadt in the Bundesliga on Saturday
Hertha will have to raise their game substantially after last Sunday's woeful 1-0 win over Hoffenheim in snowy Berlin when they mustered just one shot on goal.
Hertha Berlin reclaimed fourth spot in the Bundesliga while Ingolstadt, a newly promoted club, got the better of Darmstadt.
Salomon Kalou found the target in the 33rd and 60th minutes before completing his hat-trick with a penalty three minutes from time.
Bayern Munich defeated Hertha Berlin 1-0 to recover from their midweek Champions League defeat at Manchester City.
Dutch winger Arjen Robben hit a hat-trick on Saturday as Bayern Munich hammered Hertha Berlin 6-0 in Germany's capital but league leaders Borussia Dortmund beat Bremen to stay five points clear.
Franck Ribery scored one goal, set up two more and earned a penalty as Bayern Munich beat visiting Hertha Berlin 4-0 to extend its lead in the Bundesliga on Saturday.