An undermanned Borussia Dortmund were held to a goalless draw at Heidenheim on Friday, dropping crucial points in their bid for Champions League football next season.
Promoted Heidenheim sat deep and frustrated Dortmund into mistakes, with the visitors struggling to recapture the form which saw them win three from three to start 2024.
Dortmund, missing eight first-team players due to injury and illness, dominated possession but, besides a first-half goal to Donyell Malen which was struck off by VAR, failed to break down a determined and energetic home side.
Despite the draw, Dortmund drew level on points with third-placed Stuttgart and widened the gap on RB Leipzig, who are in fifth, to four points.
Visiting coach Edin Terzic had warned of a "difficult" task against promoted Heidenheim, who came back from 2-0 down to draw 2-2 in Dortmund in September.
Heidenheim, who sit ninth in their first ever Bundesliga season, have lost just two of 10 matches at home this season.
Dortmund were missing winger Jadon Sancho, goalkeeper Gregor Kobel and midfielders Marco Reus and Julian Brandt.
Sancho's absence was telling. The Manchester United loanee has recaptured some of his best form since returning, his creativity helping Dortmund unpick stubborn defences.
Malen looked to have given the undermanned visitors the lead midway through the first half when he collected a pass from Jamie Bynoe-Gittens and rounded the goalkeeper to score.
Dortmund celebrated the Dutchman's goal with their travelling fans, but the strike was chalked off after a long VAR review.
Heidenheim had few chances of their own but held firm.
Dortmund became increasingly frustrated as the game wore on, with Nico Schlotterbeck and Niclas Fuellkrug having their efforts saved by the energetic home goalie Kevin Mueller.
Fifth-placed Leipzig will have a chance to close the four-point gap on fourth place when they host struggling Union Berlin on Sunday.
On Saturday, leaders Bayer Leverkusen face last-placed Darmstadt away.
Bayern Munich, two points behind Leverkusen, host Borussia Moenchengladbach.