Porto surprisingly slipped up with a 1-1 draw at home to Nacional on Saturday, but Sporting were made to toil in their bid to capitalise.
Substitute Islam Slimani broke the deadlock as time ran down to move his team above third-placed Benfica on goal difference.
Estoril now lead the chasing pack in fourth after a 2-0 triumph at Rio Ave.
Luis Leal opened the scoring five minutes into the second half and the striker completed his brace in the 80th minute.
Gil Vicente are down to fifth after coming out on the wrong side of a five-goal thriller at Maritimo.
Brazilian duo Paulinho and Cesar Peixoto twice restored parity in a breathless first-half after Heldon and Derley put Maritimo ahead.
But the hosts would not be denied and Alex Soares completed the scoring in the 55th minute to move them out of the relegation zone.
Carlos Cardoza similarly eased Vitoria Setubal's fears at the bottom end of the table with the only goal against Arouca, who are now second bottom following the wins for Maritimo and Pacos de Ferreira – the latter overcoming struggling Belenenses 1-0 thanks to Fernando's first-half goal.
