RB Leipzig's early title ambitions took a dent as they lost 3-1 to Union Berlin at Stadion An der Alten Forsterei.

Oliver Burke and Ilyas Ansah struck either side of Tidiam Gomis' brilliant finish for Leipzig, with all three goals coming in a seven-minute spell in the second half, before Tim Starke secured all three points in stoppage time.

Yan Diomande and Christoph Baumgartner both tested Frederik Ronnow in the first half, with David Raum also going close with a free-kick, while Diogo Leite and Janik Haberer both failed to hit the target for the hosts in a goalless first half.

However, the game burst into life in the 57th minute, courtesy of a tidy finish from Burke. After being played into the box by Jeong Woo-yeong, Burke cut inside past Castello Lukeba and curled his effort into the top-left corner to give Union the lead.

Leipzig head coach Ole Werner responded by immediately subbing on Gomis, and the decision paid dividends on the hour mark. Gomis controlled a through ball from Conrad Harder before slashing the ball in at the near post.

But it was Ansah who had the last laugh in the 67th minute. Lazy defending from Leipzig allowed Christopher Trimmel to roam down the right wing and pick out Ansah with a pinpoint cross, with the forward guiding his header past Peter Gulacsi.

Leipzig pushed for another equaliser, but that suited Union as they threatened on the counter. Andras Schafer almost scored on the break before Starke made sure of the win in the third minute of stoppage time.

Data Debrief: Union overcome Leipzig woes

It was a clinical performance from Union, who produced 1.45 expected goals from 12 shots to Leipzig's 0.59 from nine attempts.

And although Union's attackers will get many of the plaudits, there was a crucial performance from defender Leopold Querfeld. He won 13 of his 14 duels, won four free-kicks, recorded two interceptions and made 10 clearances.

This was Union's first win against Leipzig in five attempts, while they also scored against their counterparts in as many games after four blanks.