The home side couldn’t have wished for a better start to their quest for a play-off clinching victory, as they took the lead with only three minutes on the clock.
After Sporting had failed to clear their lines inside the area, Oihan Sancet intercepted a loose ball and sent his right-footed effort into the bottom right-hand corner of the net.
This was unfamiliar territory for the home side, who had scored six of their previous seven UCL league phase goals this season after the break.
Athletic’s lead was short-lived, however, as the Lions drew level just nine minutes later when Ousmane Diomande rose highest to direct his header from Maximiliano Araujo’s corner past Unai Simon at his right post.
This was a rare moment of attacking quality for the away side, and they fell behind for the second time with the half-hour mark approaching. Gorka Guruzeta regained possession and advanced to the edge of the area before unleashing a shot which hit the left post.
It rebounded kindly back into his path, and his first-time effort from an unfavourable angle found the net at the second time of asking to give the home side a half-time lead.
Although Sporting knew their place in the knockouts was assured, there was an opportunity for the Portuguese side to sneak into the top eight of the standings and secure automatic passage to the round of 16.
And after a lacklustre first-half display, the Lions stepped it up a gear after the break and drew level just after the hour mark when a lovely piece of interplay between substitute Pedro Goncalves and Francisco Trincao freed the latter inside the area, and his low finish beat Simon to peg the hosts back for the second time.
With the home side needing to risk everything in the closing stages to find the winning goal they needed to keep their UCL hopes alive, they were caught with a sucker punch in the fourth minute of added time when Alisson Santos fired low into the bottom left-hand corner of the net to break the hosts’ hearts and send Sporting’s travelling supporters into raptures on a famous night for the 21-time Portuguese champions.
They can now look forward to advancing automatically to the round of 16, having finished above the likes of Real Madrid and last season’s finalists, Paris Saint-Germain and Inter Milan.
Flashscore Man of the Match: Morten Hjulmand (Sporting CP)