Borussia Dortmund moved back to within seven points of Bundesliga leaders Bayern Munich with a 3-0 win over 10-man Hamburg at the Westfalenstadion.
Christian Pulisic's first goal in the Bundesliga and an Adrian Ramos effort were enough for Dortmund to gain the upper hand before a red card for Hamburg goalkeeper Rene Adler allowed them to ease to victory, Ramos adding a second late on.
With four games of the season remaining, Dortmund are therefore still in the hunt for the title with Bayern only able to seal top spot next week with a win if Dortmund slip up.
Cologne all but assured themselves a place in the Bundesliga next season after coming from two goals behind to beat Mainz 3-2 at the Coface Arena.
Jhon Cordoba put the hosts in front in the ninth minute, drilling a shot into the roof of the net as Mainz had the better of the first half.
Leon Balogun added a second early in the second half, but Cologne refused to give in and pulled a goal back after a sustained spell of pressure, with Marcel Risse scoring from just outside the area.
Substitute Milos Jojic brought Cologne back on level terms with 15 minutes remaining and Anthony Modeste then put the visitors in front, much to the delight of the visiting fans.
It was Mainz's turn to respond, but they did not have enough time to get back into the game as their hopes of qualifying for next season's Champions League suffered a setback, while Cologne moved 10 points clear of the relegation zone with four games of the season remaining.