Marco Reus haunted his former side with two goals and an assist as Borussia Dortmund bounced back into form with a comprehensive win over Borussia Monchengladbach.
The Gladbach old boy opened the scoring in the 35th minute and Neven Subotic gave the defending champions a two-goal cushion at the interval.
Reus added Dortmund's third in the 70th minute before setting up Ilkay Gundogan for the fourth nine minutes later.
Jakub Blaszczykowski added a fifth as Dortmund moved up to third in the table in emphatic fashion.
Thoughts that Dortmund's title defence might already be over after a sluggish start to the campaign were soon dispelled at the Westfalenstadion.
Subotic rattled the crossbar with a powerful header in the 12th minute, and it was just a taste of things to come for Gladbach.
Reus finally broke the deadlock in the 35th minute with a fine individual goal, something the visiting fans will remember from last season, but this time it was against them.
He held off Alvaro Dominguez and, despite appearing to be off balance, still managed to put Dortmund in front.
Mario Gotze's shot was then pushed behind for a corner by Marc Andre ter Stegen, and it was a corner with consequences.
Blaszczykowski sent in a cross from the right which was met once again by the determined Subotic, who this time found the target, even though Ter Stegen got a hand to the ball.
Dortmund continued to dominate proceedings, albeit without landing the telling third blow that would have finished their visitors off.
Midway through the second half, that goal arrived from a familiar outlet.
Reus' first attempt to send the ball into the danger area came back to him, and he tried again, only this time he had spotted a gap in the far corner of Ter Stegen's goal and, rather than looking for a team-mate in the centre, he lifted the ball over the Gladbach goalkeeper and into the net.
Gundogan got in on the act in the 79th minute with Reus this time the provider with a low cross from the left and there was time for Blaszczykowski to make it five in the 85th minute, beating Gladbach's substitute keeper Christofer Heimeroth.