However, it took only another five minutes for Sporting to open the scoring, Joao Mario firing home from inside the penalty area.
The Lisbon club continued to dominate after the goal, Andre Carrillo and Slimani both being denied by Jones, but Tondela held firm to ensure that they trailed by just the one goal going into the half-time break.
The home side, playing their first ever top-flight game after winning the Segunda Liga last season, looked more confident after the break and showed signs of danger as Luis Alberto and Bruno Nascimento narrowly missed the target.
The home side were rewarded for their efforts after 58 minutes when Alberto tucked home the equaliser from close range after Sporting failed to clear their lines.
Sporting pressed for a winner as Carrillo was again thwarted by Jones, but there was a cruel sting in the tail for Tondela when Jhon Murillo brought down Gelson Martins in the penalty area in injury time.
After a short delay, Silva converted from the spot eight minutes into stoppage time to hand Sporting all three points. body check tags ::