The Dons, boosted by the appearance of Sam Cosgrove in the starting 11 having been ruled out by manager Derek McInnes in the build-up to the match, started brightly but they were quickly on the back foot.

Ojo had already gone into the book when Maxwell Acosty's strong run down the right created the opening goal. His cross found Loncar, who turned the ball past Joe Lewis at the near post.

That knocked the stuffing out of Aberdeen, and Ojo's second booking after just 20 minutes saw them reduced to 10 men and there was no way back.

There were encouraging signs for the Dons – Lewis Ferguson embarked on a weaving run from midfield before eventually losing his footing just before the half hour, but goalkeeper Andrej Prskalo remained untested.

The second goal, when it came, was almost identical to the first. Acosty again sparked the move with a run down the right, the ball this time sent to the back post where Colak headed home.

Cosgrove saw a shot blocked as the first half came to a close, and Ryan Hedges saw a 25-yard snap-shot turned away by Prskalo, but the performance saw Aberdeen booed off at the interval.

Things did not get much better after the break. With Niall McGinn already withdrawn in the wake of Ojo's red card, Cosgrove lasted just eight minutes of the second period before being replaced by Curtis Main.

But it was the visitors who continued to look the more threatening, with Shay Logan having to turn away a teasing cross from Zoran Kvrcic, and Lewis suffering a knock in dealing with the resulting corner.

For their part, the visitors were happy to sit on their lead and the second half could not have been a more low-key affair.

Rijeka stroked the ball around comfortably without ever really threatening, although they gave the distinct impression they were capable of moving up through the gears if required.