Wolfsburg picked up their first home win of the Bundesliga season and brought Bayer Leverkusen's 11-game unbeaten streak to an end with victory at the VW-Arena.
Diego set Lorenz-Gunther Kostner's side on the way to victory with two goals in the first 16 minutes before Bas Dost settled matters before half-time.
A tired-looking Leverkusen improved to hold their own in the second half, grabbing a late consolation through Stefan Kiessling, but they lost for the first time in nearly two months and missed the chance to go third in the table.
The Wolves had won at the VW-Arena once this season, but that was in the DFB-Pokal, Kostner's second game in charge.
They just needed to follow that up in the league, and Brazilian midfielder Diego inspired them to victory.
He put the home side in front after just four minutes with a trademark direct free-kick from nearly 25 yards, curled over the wall and into the corner.
He added a second 12 minutes later, scoring from much closer range this time after being given the ball by Dost.
Another Diego free-kick almost led to a third goal for Wolfsburg in the 29th minute, but Naldo's header was cleared off the line by Philipp Wollscheid with Michael Rensing beaten.
Just four minutes passed before the Wolves did register a third goal.
Diego got the move going, sending Marcel Schafer down the left, the latter sending a ball across the box for Dost to score his third goal under Kostner, and his fourth in the league this season.
Bayer were transformed in the second half, probably after a dressing down at the interval, and they did not give Wolfsburg much chance to test their defensive frailties, looking instead to find some at the other end.
Wolfsburg were happy to defend their lead and never looked in any danger of conceding until stoppage time, when Kiessling raced into the area and beat Diego Benaglio from a tight angle when the home team's defence was already heading for the dressing room.