Boulahrouz leads Stuttgart to fourth
After a goalless first half, Cacau's third strike of the season broke the deadlock before Boulahrouz sealed the win for Bruno Labbadia's men.
They had to weather an early storm to lay the foundations for the victory, though, but once they got a foothold in the game, they were more than worthy of the three points.
Kaiserslautern's Christian Tiffert had the first chance of the game, starting in central midfield and driving into the box, only to see his effort blocked by Stuttgart goalkeeper Sven Ulreich.
The home side continued to apply the pressure, and Itay Shechter could perhaps have done better when he hit wide from just inside the area.
The sense of frustration was growing around the Fritz-Walter-Stadion as the home side failed to find an opening goal, and Stuttgart did their best to increase the gloom as Boulahrouz got free in the area but could only head into the hands of Kevin Trapp.
Stuttgart take control
As a result, the sides went into the break level, but that only lasted for seven minutes of the second half. Boulahrouz, outstanding all night, laid the goal on, whipping in a low cross which Cacau crashed beyond Trapp.
The goal was all Stuttgart needed to assume control of the match and Shinji Okazaki fizzed a shot over the bar from distance as they hunted a second.
They only had to wait until the 69th minute for that to arrive, with Boulahrouz's snapshot leaving Trapp stranded after a strong run and cross from Martin Harnik.
Kaiserslautern could have made a game of it when Shechter rounded UIreich and fired wide of an open goal with 16 minutes left, but it was not to be.