A comfortable 2-0 victory for Betis at the Estadio Benito Villamarin in the first leg put them in a strong position to progress to the final four, but Jagiellonia’s imperious home form - they are unbeaten on their own turf in the Conference League this campaign - suggested the job was not done just yet.
Still, Manuel Pellegrini will have been happy at the end of the first half as his side’s two-goal cushion remained intact.
There were very few clear-cut opportunities during the opening period, with Pablo Fornals, Antony and substitute Romain Perraud - who came on for the injured Ricardo Rodriguez - amongst those to miss the target.
The hosts did have their moments, with Kristoffer Hansen finding the back of the net before it was chalked off for offside. Ultimately, the best opportunity was one that did not produce a shot as Jesus Imaz’s enticing cross agonisingly evaded Darko Churlinov and Hansen before going behind.
The ruled-out goal occurred on the brink of half-time, and that setback appeared to kill any Jagiellonia momentum that had been building.
After the restart, Betis were able to control the game with relative ease, absorbing the occasional home pressure as they looked to end the tie as a contest on the counter-attack.
Giovanni Lo Celso curled narrowly over the crossbar from the edge of the area, before Cedric Bakambu fired into the roof of the net from close range to all but end the tie as a contest.
While Churlinov did net a composed equaliser shortly after, three goals always looked to be a bridge too far for the hosts.
Betis are now unbeaten in their past six matches in all competitions, and they will now face Fiorentina in a duel between two of the pre-tournament favourites.
Jagiellonia, meanwhile, can be immensely proud of their run in what is their maiden campaign in the main draw of a UEFA competition. They still have plenty to play for this season, too, with a second consecutive Polish Ekstraklasa title still within their grasp.
Flashscore Man of the Match: Cedric Bakambu (Betis)