WATCH the Bundesliga LIVE on beIN SPORTS | Sign up to take advantage of our 7-day FREE TRIAL here | AU | NZ

Dortmund, which had a midweek confidence boost with a 1-0 home win over Sturm Graz in the UEFA Champions League, struggled against the hosts and were left with 10 men in the 27th minute when captain Can launched a reckless studs-up challenge on Lee Jae-Sung and received a straight red card.

Things got even worse when the Korean rose to nod a deft finish past Alexander Meyer to give Mainz the lead in the 36th minute.

However, Lee then brought down Serhou Guirassy in the box just four minutes later, with the striker restoring parity from 12 yards.

Dortmund could not hold on until half-time though, as its defence was again caught out when Jonathan Burkardt turned in a cutback in first-half stoppage-time.

After the break, Mainz picked up where it had left off, bagging a third goal through Paul Nebel, who coolly slid in from the edge of the six-yard box in the 54th minute.

Dortmund, which has lost four of its five away league matches this season and drawn the other, is on 16 points in seventh spot. Mainz is three points behind in 10th.

Dortmund coach Nuri Sahin made no excuses after another dismal away performance.

"A difficult away game for us. Once we got that red card it got really hard," Sahin said.

"We have too few points on the road though I have to analyse today's defeat a bit differently than the other defeats because of the red card.

"With a few more points we would be somewhere else in the table. But for us we just are getting too few points.

On the red card, Sahin was critical of his captain.

"Emre can't go into this challenge like that," Sahin said.

"He wins the first ball and then in the second effort he should stay up."