Though written off as hopeless cases by almost everyone before kickoff, Les Unionistes came out aggressively at the Johan Cruyff Arena. Yet, that very nature almost saw them concede inside five minutes, as Steven Berghuis delivered an inviting free-kick that Jorrel Hato headed wide.
That intensity paid dividends around the quarter-hour mark though, as the visitors halved their aggregate deficit from the first leg with a free-kick of their own. On his first start since returning from injury, Sofiane Boufal won and delivered the set-piece that was headed home by Kevin Mac Allister.
Boufal then had the ball in the net himself just three minutes later but the goal was ruled out for offside.
Undeterred, Royale Union kept flying forward, with Ousseynou Niang’s strike being denied by Remko Pasveer’s legs.
The winger then hit a shot that was desperately palmed away by Davy Klaassen, resulting in not only a red card for de Godenzonen’s captain, but also a penalty that Promise David converted by sending Pasveer the wrong way.
Ajax now looked completely lost after entering the evening’s contest in a relatively comfortable position, and while Boufal, Franjo Ivanović and Anan Khalaili sent efforts over the crossbar to give the hosts a series of letoffs, there was another blow for them before half time, as Christian Rasmussen went off injured.
Francesco Farioli responded with three substitutions and a change of formation ahead of the restart. That initially did nothing to turn the momentum, with Kōki Machida’s header being saved and Ivanović shooting agonisingly wide inside five second-half minutes.
But they eventually started to compete more, even though Pasveer marginally reached Machida’s header before David, who then had a header of his own blocked with the atmosphere growing increasingly tense as time passed in the Dutch capital.
Bertrand Traoré almost provided a moment of inspiration for the hosts late on but was ultimately denied by Anthony Moris, who then palmed Mika Godts’ attempt into the side netting as the match went to extra time.
Determined to win it for their exhausted and stressed-out fans, Ajax got a penalty just two minutes after the restart when Christian Burgess handled Traoré’s cross, and Taylor deceived Moris to put his side ahead in the tie.
There was still time enough for some tense moments of course, and Pasveer awkwardly tipped Ivanović’s shot wide to deny the visitors an instant response, and stopped an effort apiece from Mohammed Fuseini and Kevin Rodríguez.
That ensured Ajax would set up a UEL Round of 16 tie against Eintracht Frankfurt or Olympique Lyonnais, despite their five-game winning run across all competitions coming to an end.
They also inflicted heartbreak on Saint-Gilloise, whose gutsy win at such a famous ground will always be remembered for the sour note of elimination.
Flashscore Man of the Match: Promise David (Royale Union Saint-Gilloise)