Didier Drogba's first goal since January 24 rescued a point for Carlo Ancelotti's side after Jon Walters had fired Stoke ahead at the Britannia Stadium.
But the result almost certainly ended Chelsea's remote title challenge, Ancelotti's side now 11 points before leaders Manchester United with eight games remaining.
Manchester United's 4-2 victory over West Ham earlier in the day meant Chelsea had to win all of their remaining nine games to stand any chance of retaining the title.
But, with Fernando Torres starting on the substitutes bench ahead of next week's Champions League quarter-final first leg with United, Ancelotti's team got off to the worst possible start.
Former Chelsea defender Robert Huth had already headed over the bar when Walters got the better of David Luiz just inside the visitors' half before embarking on a powerful run.
Walters, a 2.75 million pound signing from Ipswich in August, cut inside the Chelsea area before picking his spot after neatly wrong-footing Michael Essien.
Chelsea, who had won six of their previous eight league games, responded through Ashley Cole's header from 12 yards, saved by Asmir Begovic, and a volley from Florent Malouda which flashed narrowly wide of the target.
But they endured a major scare in the 24th minute when John Terry went down after a hefty challenge with Glenn Whelan, the Chelsea captain only getting to his feet after receiving treatment.
Ancelotti wore the look of a man with plenty of problems but the Italian was smiling again when Chelsea conjured up a 33rd-minute equaliser after great play from his forwards.
The Chelsea manager had raised eyebrows by leaving Torres out, but his selection was vindicated as his preferred front pairing combined to draw Chelsea level, Nicolas Anelka's cross headed home brilliantly on the dive by Drogba.
