The Spain international's future has been a source of constant speculation this season and he was recalled to Zinedine Zidane's first XI as one of nine changes from the Champions League win at Bayern Munich in midweek.
A superlative solo goal from the 24-year-old in the 17th minute got Madrid on terms, three minutes on from Duje Cop's equally enjoyable opener.
On-loan Athletic Bilbao midfielder Mikel Vesga inventively made Sporting's first and put them ahead again with his first LaLiga goal five minutes into the second half.
Alvaro Morata, leading the line as Cristiano Ronaldo, Karim Benzema and Gareth Bale sat out, headed his 12th league goal of the season for Madrid's second equaliser and, with eight seconds of normal time to play, Isco screamed for the ball on the edge of the box and rifled an unerring strike into the bottom left corner.
The result puts the pressure back on Barcelona, who must beat Real Sociedad later on Saturday to avoid the gap at the summit being greater than three points when the Santiago Bernabeu hosts El Clasico next weekend.
Heartbroken Sporting are five points from safety with six games remaining and Rubi will wonder why it took the visit of the European champions to produce such a performance.
Lucas Vazquez powered over from Danilo's superb left-wing cross when he should have opened the scoring – something Sporting did in style soon afterwards.
Vesga was the architect of his side's first home goal against Real Madrid since October 1994, scooping a wonderful pass over the visitors' defence and Cop followed the flight of the ball expertly before dispatching a left-footed volley beyond Kiko Casilla.
Sporting's joy was short-lived as Isco was allowed a touch too much room inside the area, shuffled away from Carlos Carmona, skipped past Vesga and Fernando Amorebieta, and lashed a shot into the top corner for a similarly high-quality equaliser.
A sliding Jorge Mere scrambled James Rodriguez's low cross away from the Sporting goal line in the 37th minute after Mateo Kovacic pulled the hosts apart on the break.
Lucas fired over in trying to emulate Isco's earlier heroics but Madrid could not turn sustained pressure into a half-time lead.
Isco continued to mesmerise the Sporting defence when the action resumed and, after he won a free-kick in a dangerous position on the left, James picked out Nacho, whose header was stunningly kept out by Ivan Cuellar.
Once again, following a close shave, Sporting hit the front. Nacho fouled Cop and Jean-Sylvain Babin headed Carmona's lofted delivery towards the penalty spot, where Vesga cleverly looped a header past the scrambling Casilla and into the corner.
Rubi saw his team's lead last a comparatively lengthy nine minutes this time around, with Danilo opting against a long-range attempt to flight an inviting ball for Morata leap above Babin and head home.
Sporting wing-back Isma Lopez stormed into the Madrid area to drag a shot wide, while a familiar source caused mayhem at the other end with 18 minutes to play.
Isco dazzlingly shimmied in and out of increasingly desperate Sporting challenges before substitute Marcelo blasted the loose ball wide.
Lucas' angry kick at the bench when he was substituted late was a useful summary of the frustration consuming his Madrid team-mates until Isco bailed them out magnificently – making his most convincing argument to date that he deserves to be more than a supporting character under Zidane.
Key Opta stats:
- Isco has had a hand in nine goals (seven scored, two assisted) in his last eight LaLiga starts for Real Madrid.
- Sporting hadn't scored twice against Real Madrid in a LaLiga game since April 1994 (2-2).
- Alvaro Morata has scored 12 goals this La Liga season, three more than Benzema.
- Real Madrid have scored in their last 54 matches in all competitions. This is the best run by any LaLiga team.
- Real Madrid are the side in the top five European Leagues with the most headed goals scored this season (25).