The Werkself's evening started as it would go on, as Fin Bartels opened the scoring early in the match - putting Bremen in the driving seat despite their poor form.
Claudio Pizarro would be the star of the show, though, as he scored a second half hat-trick. Papy Djilobodji's own goal was the only blemish on a near-perfect night for Bremen.
Bartels brings Bremen in front
The game got off to an awful start for the hosts, who fell behind inside five minutes. A long ball into the box was directed towards the back post and Papy Djilobodji, who managed to keep it in play. His knock-down fell perfectly to Fin Bartels, who lashed a half-volley through Tin Jedvaj and Bernd Leno's legs to shock the BayArena faithful.
The hosts were struggling to get going and the continued long balls to Javier Hernandez were greeted with whistles by the home fans, Hakan Calhanoglu looked to be their only bright spark but even he struggled to find a way through. The closest Leverkusen came was from Roberto Hilbert, who only found the side netting with a strong shot.
Roger Schmidt's absence on the touchline was seemingly having an effect on their form, as they looked all out of ideas against a deep Bremen defence. The visitors were finding things hard to come forward themselves, though their early goal was enough to see them go into half-time with a lead.
Pizarro rolls back the years
Leverkusen needed things to change and fast, bringing on Robbie Kruse for the quiet Julian Brandt at the break. That did seem to pay dividends with the hosts' first major chance coming soon after. Hernandez was fed through on goal but Felix Wiedwald made a smart save with his feet.
While things looked to be taking a positive turn, a silly mistake changed all that. Christoph Kramer was robbed of the ball in midfield and Claudio Pizarro took full advantage. He drove towards goal, lifted his head to look at the advancing Leno and calmly chipped over the oncoming 'keeper to extend Bremen's lead.
Just when the evening couldn't get any worse for the hosts, it did. Zlatko Junuzovic was about to pull the trigger after some stylish build-up play, only to have his legs taken from underneath him by Wendell. Marco Fritz pointed to the spot, and Pizarro called on all his experience to keep calm and send Leno the wrong way.
Leverkusen's woeful evening in front of goal did take a more positive turn in the latter stages of the game when Djilobodji put through his own net. A cross from the left was met by the on loan defender, who curiously tried to head back towards Wiedwald from close range and only succeeded in lobbing his own goalkeeper.
Any tempo had been completely zapped from the game at this stage, and some shocking goalkeeping and defending combined to hand Bremen a fourth. Junuzovic, who finally showed what he is capable of for one of the first times all season, picked out Pizarro to head past Leno; the 'keeper had ended up in no man's land. That was the final moment of note from the game as the visitors rose to 15th. Leverkusen, on the other hand, sit seventh with four points between themselves and fourth.