Dutch striker Ricky van Wolfswinkel and Argentine Fabian Rinaudo both scored to help Sporting beat 10-man Nacional 3-1 on Wednesday and secure a berth in Portugal's cup final.
Hosts Nacional started strongly and hit the bar in the opening minutes but it was Sporting midfielder Rinaudo, back after a long injury, who scored the opener with a cleanly-taken drive in the 17th minute.
Sporting coach Domingos Paciencia had flagged the domestic cup as his new priority after a poor run of form left his side trailing 13 points behind leaders Benfica, in fourth place in the Portuguese Premier League.
Paciencia's ambitions hung in the balance when Nacional forward Diego Barcellos headed an equaliser in the second half.
Sporting had travelled to the Atlantic island of Madeira needing a win or a goal-filled tie after they were held to a 2-2 home draw in the first leg.
The visitors got their breakthrough when Wolfswinkel converted from the spot to put Sporting back in front with 20 minutes to go and breathed a sigh of relief deep in stoppage-time when Joao Pereira made it 3-1.
"We suffered to win this one but we battled on and should congratulate ourselves," Paciencia told journalists.
Sporting will meet Academica in the cup final.comments