Isco picked out the top corner at the end of a jinking solo run in the 17th minute after Duje Cop had opened the scoring for relegation-threatened Sporting in equally memorable style.
Alvaro Morata netted Madrid's second equaliser to cancel out Mikel Vesga's early second-half header and, just when it looked like the leaders were set to leave the door ajar in the title race, Isco lashed a rasping low shot from the edge of the box beyond Ivan Cuellar's despairing dive.
The 24-year-old has been regularly linked with a move away from Madrid during Zidane's tenure – including a switch to bitter rivals Barcelona.
His selection as one of nine changes from Wednesday's 2-1 Champions League win over Bayern Munich underlined his back-up status in an all-star squad, although his Molinon heroics may cause Zidane to think again on that front.
"Isco played a great game. I am happy with how he played, he made the difference, his goals got us the three points," the Madrid boss said at a post-match news conference.
"Isco is a great player and he has shown that Madrid is where he belongs. He has shown with his performance that he is a great player.
"If I have been unfair to Isco I have been unfair to all who do not play. In the end we are 24 players and everyone can play outside of Real Madrid.
"This is the difficulty of this position, to put good players on the bench from time to time.
Barcelona must now beat Real Sociedad in Saturday's late kick-off to ensure they remain within three points of Madrid ahead of next weekend's Clasico at the Santiago Bernabeu.
It was the sixth time this season Madrid have won a LaLiga game inside the final 10 minutes but Zidane refuted suggestions he is in charge of a lucky side.
"In football there's no luck," he said. "There's lot of hard work, effort in every game, every moment, every ball.
"You must make your own luck. They had two chances and two goals. In the end it is a well-deserved result.
"We know that with the team we have we can do damage to any team and fighting to the end to get three points is in our DNA at Real Madrid."