Peruvian Paolo Guerrero scored twice in the second half to give visitors Hamburg SV a 2-1 win over Schalke 04 on Sunday which put them within a point of leaders Hertha Berlin.
Guerrero scored both goals within four minutes in the second half as Hamburg joined Bayern Munich and VfL Wolfsburg on 48 points with nine league matches left.
The defeat leaves Schalke, who have yet to replace sacked general manager Andreas Mueller, in eighth place on 37 points and is certain to fuel speculation about the future of coach Fred Rutten.
"I am very proud of my team. Schalke had nine days to prepare for this while for us it was the 11th match in 33 days," Hamburg coach Martin Jol told reporters. "This is amazing. I did not expect that."
Hamburg have progressed in the UEFA Cup and now face Manchester City in the quarter-finals. They have also qualified for the German Cup last four where they will take on Werder Bremen.
With Guy Demel and Michael Gravgaard fit again, the Hamburg defence looked far more solid than in recent weeks and gave Schalke no real scoring chances.
Jonathan Pitroipa was unlucky not to score for the visitors on the half-hour mark when Schalke's Levan Kobiashvili passed the ball back to his keeper only for the Burkina Faso striker to pounce and lob the ball over the crossbar.
Uninspiring Schalke were either caught offside or saw their long-range efforts sail high, wide or get blocked.
The lacklustre encounter seemed destined for a draw but Guerrero took advantage of a mistake by Schalke keeper Manuel Neuer, who failed to clear a long kick from Hamburg keeper Frank Rost, to slot home in the 71st.
Guerrero quickly made sure of the points four minutes later when Marcell Jansen crossed low into the box and the Peruvian struck from three metres.
Jefferson Farfan scored from close range 10 minutes from time but despite piling on the pressure in search of a late equaliser Schalke had to settle for their eighth league defeat of the season.
Hertha still lead on 49 points despite losing 2-0 to VfB Stuttgart on Saturday while Bayern beat bottom-of-the-table Karlsruhe 1-0 and Wolfsburg scored their seventh consecutive win, a 3-0 victory over Arminia Bielefeld.