Bayer Leverkusen 1 Borussia Dortmund 1: Yarmolenko strike rescues visitors
Dortmund went into the game with Bosz under intense pressure after a run of six games without a win, but his side fell behind after half an hour.
Kevin Volland's opening goal came after a defensive howler from Neven Subotic, but Leverkusen then had Brazilian full-back Wendell sent off just before half-time.
Against 10 men, the visitors dominated the second half possession but failed to break down Heiko Herrlich's well-drilled outfit until Andre Schurrle teed up Yarmolenko for his third league goal of the season.
Despite salvaging a point, the laboured nature of Dortmund's performance with a man advantage against a side below them in the Bundesliga standings might lead the club's board to make a decision over Bosz's future before the trip to face Real Madrid in the Champions League on Wednesday.
Punkt. #b04bvb 1-1 FT. pic.twitter.com/qVCMUKSMRv
— Borussia Dortmund (@BVB) December 2, 2017
Bosz was forced into an early substitution when Maximilian Philipp was stretchered off with a serious knee injury after seven minutes, and Schurrle replaced him in attack for the visitors.
Former Dortmund defender Sven Bender aimed a header towards goal five minutes later but Roman Burki, returning to the BVB side after recovering from a concussion, made a reflex save and parried the ball around the post.
Burki rescued Dortmund again moments later when he made a one-handed save to keep Julian Brandt's bouncing volley from finding the net, before Yarmolenko gave Bayer goalkeeper Bernd Leno his first test with a low, angled drive that was comfortably saved.
The goal the game had threatened finally materialised on the half hour after Neven Subotic made a hash of what should have been a straightforward pass on the half-way line.
Kai Havertz took full advantage, sending a pass into the path of Volland who rounded Burki 30 yards from goal before rolling the ball into the empty net.
The home side's momentum was spoiled by Wendell, whose crunching challenge on Gonzalo Castro earned him a straight red card after 43 minutes, referee Robert Hartmann using VAR before making his decision, and left the Dortmund midfielder unable to continue.
Yarmolenko had a claim for a penalty waved away early in the second half after going down under a challenge from second-half substitute Panagiotis Retsos, and Shurrle hit the side-netting in the 55th minute after a superb back-heel pass by fellow substitute Shinji Kagawa.
With just under 20 minutes left, Burki made a vital intervention when he saved from Volland at close range and one minute later the visitors broke down the left wing, where Schurrle sent over a low cross that Yarmolenko controlled before poking the ball past Leno and into the net.
#sempresempreavanti #b04bvb 1-1 pic.twitter.com/5bJXAktKoE
— Borussia Dortmund (@BVB) December 2, 2017
Dortmund pressed for a winner but struggled to find a way through a packed Leverkusen defence, while Leon Bailey had a dipping free-kick saved by Burki at full stretch at the other end, and ultimately the full-time whistle brought with it frustration for both managers.