Joleon Lescott looked to have boosted the Toffees’ push for a Champions League spot with a 78th-minute header for his ninth goal of the season.
But five minutes later, sub Zarate hammered a 20-yard drive past Everton keeper Tim Howard to salvage a share of the spoils for the home side.
It was no more than Blues deserved after dominating the second period only for poor finishing and some superb saves from Howard to deny them victory.
After 78 minutes, Lescott put Everton ahead. Andy Johnson’s cross was flicked on by Yakubu and Lescott headed home.
But Blues roared back and Zarate curled a free-kick past Howard to rescue a point, leaving them two points clear of the drop zone.