Karim Adeyemi supplied Daniel Svensson's opener before the half-hour mark and Carney Chukwuemeka added Dortmund's second early in the second half, his first goal since signing from Chelsea in the summer.

Dortmund promised more stability after starting their European campaign with a wild 4-4 draw at Juventus, but invited Bilbao into the match, handing Gorka Guruzeta a goal with a defensive mix-up on the hour.

Dortmund looked shaky, but Guirassy calmed their nerves, getting a boot to a Marcel Sabitzer shot to restore their two-goal lead with nine minutes remaining.

Julian Brandt then added a fourth for the hosts to wrap up the match in stoppage time. Making their first Champions League appearance since 2014/15 and just their third overall, Bilbao missed the creativity of the injured Nico Williams.

The loss was their fifth in six games without the Spain winger, having scored just twice in that time. Despite an unbeaten start to the season, coach Niko Kovac made good on his pre-match promise to rotate the side and get more minutes into the legs of his bench players.

Jobe Bellingham started his first match since August, while Chukwuemeka made his full debut in the starting line-up. Dortmund's lack of fluidity was evident early, particularly for Bellingham, who struggled to find his passing range.

The in-form Adeyemi created Dortmund's opener, burning down the right flank and threading a pass across the face of the goal for Svensson to tap home.

The goal sparked Dortmund into life, but their decision-making was poor. Niklas Suele, making his first appearance of the season, opted for a long-range effort rather than passing to the unmarked Guirassy inside the box.

Chukwuemeka doubled Dortmund's lead in the 50th minute, blasting in at the near post after being put into space by Guirassy.

Dortmund looked on course for a routine win but invited Bilbao back into the match with a clumsy defensive error. Suele failed to clear a ball in the box, which fell to Guruzeta, who scored with ease. The goal put the fright into Dortmund, who struggled to get out of their own half.

Bilbao had a handful of half-chances to draw level and a goal ruled out for offside, but Guirassy would put the hosts on track again, deflecting Sabitzer's shot into the goal for his sixth goal in seven games this season. Brandt provided further gloss to the scoreline at the death.

C. Chukwuemeka

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