Stefan Kiessling took advantage of an error by Stuttgart goalkeeper Sven Ulreich to steer Bayer Leverkusen to back-to-back Bundesliga wins.
The Germany forward was on the mark in the 28th minute at the Mercedes-Benz Stadion to give Champions League group stage qualifiers Leverkusen six points from three league games, while for Bruno Labbadia's Stuttgart side it was a first defeat of the season.
The decisive moment came when Michal Kadlec's long-range effort drifted towards goal and Ulreich allowed the ball to bounce, ensuring Kiessling had time to nip in front of him and put the visitors in front.
Stuttgart full-back Khalid Boulahrouz made a storming run in a bid for a quickfire equaliser but the former Chelsea man fired over the top, and Leverkusen led at the break.
Robin Dutt's men almost doubled their lead after 55 minutes when Sidney Sam latched onto Renato Augusto's cross from the right but pulled his shot wide, before the hosts missed a glorious chance to draw level midway through the second half.
Cristian Molinaro crossed from the left to the far post, Shinji Okazaki steered the ball back across goal but Cacau somehow failed to make contact on what should have been a tap-in.
There was no way back for Stuttgart, who were reduced to 10 men in the final seconds when Boulahrouz was shown a second yellow card for dissent, having been booked earlier in the game for a foul on Simon Rolfes.
