Adeyemi's goal came during a period of sustained dominance from the visitors early in the second half, with the Germany forward pouncing on a clearance from a Chelsea corner.

Adeyemi sensed the opportunity and ran the length of the field, rounding both Enzo Fernandez and goalkeeper Kepa Arrizabalaga to give Dortmund the crucial lead which took them to victory.

While Chelsea manager Graham Potter may still be working on how to get his squad of expensive newcomers to work as a team, the visitors' individual quality and speed on the counter was obvious throughout.

Mykhailo Mudryk's pace troubled the home side frequently early and forced Dortmund central defender Niklas Suele into a looping backheeled clearance after 15 minutes.

Chelsea were soon on the attack again through Mudryk, who won a free kick to the left of the penalty area.

Chelsea had the ball in the back of the net through Thiago Silva from the free kick but the home side swarmed referee Jesus Gil Manzano in protest.

A VAR review showed the Chelsea captain had intentionally handled the cross and Silva was promptly booked.

Dortmund's Julian Brandt and Jude Bellingham continued to orchestrate attacks as the home side dominated possession, which left them vulnerable to Chelsea's counter-attacking raids.

The best chance of the opening half fell to Chelsea's Joao Felix, who muscled past Dortmund fullback Marius Wolf inside the box to give himself space to shoot, but his attempt hit the crossbar.

Wolf almost had Dortmund in front close to halftime when Brandt shrugged a defender to put him in space just inside the penalty area, but his curling shot drifted wide.

Chelsea dominated the early stages of the second half, forcing Dortmund midfielder Emre Can into a yellow when he took down an advancing Reece James.

Goalkeeper Gregor Kobel saved the free kick to ease the pressure.

James went one-on-one with Kobel again after 60 minutes, this time in open play, but the Swiss 'keeper tipped his shot over the bar.

Chelsea's corner pinballed around in the box and despite an offside flag, the referee played the advantage as the ball was cleared into the path of Adeyemi.

The Germany forward, who was officially clocked as the fastest player in Bundesliga history earlier in February, kicked the ball past an advancing Fernandez and then Kepa, threading the ball into the goal from an acute angle.

Chelsea looked certain to score in the 78th minute when Kalidou Koulibaly's shot dribbled goalwards, but Can intervened to clear the danger, booting the ball to safety before it crossed the line.