Senegal appeared on course for a first win in a World Cup knockout match since their 2002 debut after taking a 2-0 lead through strikes from Habib Diarra and Ismaila Sarr in Seattle.
However, Belgium forced extra time as Romelu Lukaku and Tielemans scored in the final five minutes, before the Aston Villa midfielder completed a remarkable turnaround by converting a penalty in the 125th minute.
A defeat would surely have signalled the end of the road for the last remnants of Belgium’s golden generation – Lukaku, Kevin De Bruyne and perhaps Thibaut Courtois – but instead they live to fight another day.
After a 5-1 win over New Zealand that clinched top spot for Belgium in Group G, Rudi Garcia named an unchanged side with Atalanta forward Charles De Ketelaere leading the attack and Lukaku on the bench.
Senegal coach Pape Thiaw made three changes to the side that thrashed Iraq 5-0, which allowed them to squeak through as the last of the eight best third-place teams.
Pape Gueye started after scoring twice as a substitute in that match, while Pathe Ciss and Everton winger Iliman Ndiaye came into the line-up.
Senegal nearly went ahead through the in-form Sarr, who hit the post after Courtois inadvertently diverted a cross into the Crystal Palace forward’s path.
The Lions of Teranga did take the lead, however, when Sarr’s header from Sadio Mane’s cross came back off the same post, with Diarra reacting quickest to turn the rebound home.
Belgium unsurprisingly turned to their all-time leading scorer at the interval, with Lukaku having already proven his value as a substitute against Egypt and New Zealand in the group phase.
But Belgium fell further behind six minutes into the second half when Sarr chested down Moussa Niakhate’s long pass over the defence before firing an emphatic finish beyond Courtois.
De Bruyne and Jeremy Doku were hauled off as Belgium appeared to be heading out, but Lukaku – limited to barely an hour’s play with Napoli this season – grabbed his team a lifeline in the 86th minute.
He swept home from a Thomas Meunier cross and, just three minutes later, Belgium were level. Diaw failed to deal with Leandro Trossard’s delivery into the box and Tielemans held off two defenders to nod into an empty net.
Belgium substitute Dodi Lukebakio clipped the crossbar late in the second period of extra time as the match appeared destined for a penalty shootout.
But there was one final twist when Tielemans went down under a challenge from Lamine Camara, prompting referee Said Martinez to award a penalty after a VAR review.
Tielemans stepped up and dispatched with aplomb to cap a stunning fightback and break Senegalese hearts. (AFP)
