Borussia Dortmund's title hopes suffered another blow on Saturday afternoon, with a 3-2 defeat at home to Wolfsburg leaving the defending Bundesliga champions 14 points adrift of league leaders Bayern Munich.
The game started well enough for Dortmund with Marco Reus giving them the lead in the sixth minute, but a red card for Marcel Schmelzer and penalty from Diego, followed by Naldo's volley, turned the game in Wolfsburg's favor.
Although Jakub Blaszczykowski leveled for Jurgen Klopp's men after an hour, Bas Dost netted the winner for the Wolves, who climb seven points clear of the relegation zone as a result.
Despite picking up an ankle injury in training on Friday, Diego was passed fit to play and he set up the first chance of the match for Wolfsburg, but Makoto Hasebe's cross was too powerful for Dost.
Dortmund were then given a free-kick just to the left of the penalty area and Reus stepped up to send his shot into the far corner without the need for a touch from a team-mate as it beat Diego Benaglio.
Dortmund were dominating, but could not find a second goal with Robert Lewandowski and the lively Schmelzer missing their best chances.
Things took a turn for the worse for Schmelzer and Dortmund in the 35th minute when he blocked Dost's shot on the goal line with his hand, according to the referee, who gave a penalty and showed the Dortmund defender the red card.
Diego stepped up to the spot to bring Wolfsburg level.
Five minutes later, Diego turned provider with a free-kick which was met by central defender Naldo on the volley, and he dispatched his shot into the bottom corner of Roman Weidenfeller's goal to turn the game on its head.
The second penalty of the afternoon was awarded in the 61st minute, although Simon Kjaer got away with only a yellow card for fouling Lewandowski inside the penalty area.
His Polish compatriot Blaszczykowski stepped up to the spot to equalize for the Westphalians with half an hour of the game to go.
The 10 men of Dortmund raised the tempo again in search of a winner, but they were caught out in the 73rd minute when Diego threaded a pass through to Dost, who had only Weidenfeller to beat, and he duly obliged to give Wolfsburg the lead once again.
This time, it was too much for the defending champions, who were unable to summon up the energy for a late assault on a point.