Bayer Leverkusen battled past Mainz 05 2-1 on Friday to go 11 points clear at the top of the league and set a new record for a Bundesliga club with their 33rd straight game without defeat across all competitions.
The Bundesliga leaders, who lacked their usual efficiency up front while also allowing the visitors enough space to attack, needed a mistake by Mainz keeper Robin Zentner to snatch the win.
Xabi Alonso's team, who beat Bayern Munich's previous unbeaten run of 32 matches, are now on 61 points, with second-placed Bayern, on 50, in action against RB Leipzig on Saturday.
They went in front with Granit Xhaka's stunning effort from 20 metres in the third minute but it was shortlived with Dominik Kohr's diving header just five minutes later levelling things for Mainz.
Leverkusen had possession but Mainz keeper Robin Zentner made a string of fine first half saves to keep the visitors in the game before letting a weak Robert Andrich shot in the 68th slip through his hands for the hosts to reclaim the lead.
Mainz goalkeeper Robin Zentner made a costly mistake part way through the second half
Robert Andrich's speculative strike from range earned Leverkusen a hard-fought victory
Xabi Alonso had fumed at a few referring decisions in the first half before his side were able to claim the win and move 11 points clear at the top
Mainz were left with 10 men when Jessic Ngankam was sent off for a foul on Xhaka.
'We have to be honest to ourselves and say that we did not play a good game,' said scorer Andrich. 'We were a bit lucky to win it. But we won't be complaining about the three points.
'We were too impatient and not precise enough. We did not find the solutions needed. We made far too many mistakes.'