Zaha notched at the home of the Foxes for the fourth game running - his sixth goal in total against Leicester - after just 12 minutes of Monday night’s entertaining Premier League contest in the East Midlands, expertly finishing off a swift counter-attack after being teed up perfectly by Eberechi Eze’s pass to equal his best top-flight scoring campaign to date (10).
However, Leicester battled back to turn the game around after the interval, with Timothy Castagne notching the equaliser just five minutes into the second half before a special goal from in-form striker Kelechi Iheanacho - who also set up the opener - sealed a hard-fought win late on.
It was the Nigerian international’s 10th Premier League goal of the season and his 14th in his last 14 appearances for Leicester, who took a huge step towards qualification for next season’s Champions League.
Brendan Rodgers’ third-placed side - who have also reached the FA Cup Final for the first time since 1969 - now hold a seven-point buffer to West Ham in fifth with only five matches left to play this term.
Palace, meanwhile, have now won only one of their last seven matches and a 14th league loss of the season sees them stay 13th ahead of a likely summer of big change in south London.
Zaha gave Palace the lead after Vicente Guaita had denied the busy Jamie Vardy in the opening minutes at the King Power, with Youri Tielemans dispossessed by a robust challenge from Christian Benteke in the build-up.
Leicester flattered to deceive after going behind and a VAR check for a potential penalty just before half-time came to nothing after a challenge on Iheanacho.
But it did not take long for the Foxes to restore parity after the interval, with Belgian full-back Castagne smashing into the top corner after a lay-off from Iheanacho.
The goal stood after another two VAR checks - one for handball and another for a possible high boot by Iheanacho on Cheikhou Kouyate.
Jonny Evans’ excellent last-ditch challenge later denied Benteke a potential tap-in after Jairo Riedewald broke through for Palace and Guaita denied James Maddison and Vardy before Benteke then headed a corner straight at Kasper Schmeichel.
A Vardy effort was rightly chalked off for offside with 20 minutes left and the former England frontman and Tielemans then both shot wide before Iheanacho’s decisive intervention.
The ex-Manchester City forward did well to control a long Evans pass and cut inside Scott Dann before beating Guaita with a powerful effort that flew in at the near post.