Florian Wirtz made his return from injury, but couldn't help his Bayer Leverkusen avoid a setback in the Bundesliga title race in a goalless home draw with Union Berlin on Saturday.
Leaders Bayern Munich can now open an eight-point gap if they win the top clash against Borussia Dortmund later.
Leverkusen star Wirtz started on the bench after had been sidelined since early March due to a ligament injury in his right ankle. He came on in the 57th minute, but the defending champions couldn't do better than a draw.
Union were able to find the net in the 15th minute as Leopold Querfeld slided the ball over the line in the rebound from a Lukas Hradecky save, but he was offside and the goal was ruled out.
"It wasn't a good day for us. We lacked a bit of energy in the final third. We missed the opportunity to build up pressure. The season isn't over yet, we still have to look forward," coach Xabi Alonso said in a news conference.
The other games
Mainz, meanwhile, dropped out of the Champions League qualification zone after a 2-0 defeat to Hoffenheim, who were led to victory by Andrej Kramaric's brace.
Mainz lost the position to RB Leipzig, who on Friday defeated VfL Wolfsburg 3-2.
In the battle for the Conference League, Johan Manzambi scored a late goal to give Freiburg a 2-1 win at Borussia Mönchengladbach and help his team leapfrog Gladbach for the spot for the European competition.
Elsewhere, 10-man Augsburg claimed a late 2-1 win at lowly Bochum, while St Pauli Hamburg are now seven points above the drop zone thanks to a 2-1 win in stoppage-time at bottom side Holstein Kiel. St Pauli's winner was an own goal from Max Geschwill.
