Ivan Gattuso Jakov Puljic and Mario Gavranovic scored the goals as Rijecka handed AC Milan a first defeat in this season's Europa League.
Following their famous UEFA Europa League win over F91 Dudelange, University College Dublin take on Slovan Bratislava on Thursday.
Emmanuel Adebayor Ajax failed to make it into the Champions League group stage for the third year in a row, with Nice triumphing on away goals.
There will be no debut Champions League campaign for Nice in 2017-18 after Napoli cruised to a 4-0 aggregate victory.
Tottenham Hotspur Tottenham booked their place in the last 32 of the UEFA Europa League with a 2-1 win over Sheriff on Thursday.
Sligo Rovers Sligo Rovers and Inter Baku will look to convert first-leg shocks to progression from the UEFA Europa league second qualifying round.
Olympique Lyon Lyon and Real Sociedad were the big-name casualties in the UEFA Europa League play-offs on Thursday.
Inter Milan Italian giants Inter visit Stjarnan in Iceland while Villarreal, Tottenham and Feyenoord also begin their UEFA Europa League play-off ties on the road.
Ivan Gattuso AC Milan boss Gennaro Gattuso insisted there is so much to gain in Croatia on Thursday amid the club's woes domestically.
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