Chelsea failed to beat Everton at Goodison Park for the second time this season - and almost found themselves dumped out of the FA Cup.
Everton held the champions to a 1-1 league draw in October and this time the scoreline was the same and so was the Chelsea saviour - Frank Lampard.
David Moyes's men had taken the lead through a James McFadden first-half header, before the Scot went off with a facial injury after a crunching challenge from Carlo Cudicini.
Chelsea were fighting desperately to save themselves from what would have been only their fourth defeat of the season - but up popped Lampard in the 73rd minute to force a Stamford Bridge replay.
Everton, missing 10 first-team squad members even before McFadden's exit, produced another brave display to stand alongside the 1-0 victory they achieved over Arsenal here the previous week.
They have now gone seven games without defeat and at least their season is no longer heading for relegation, although they must view a replay as a dubious honour.
Everton's selection problems worsened before the match when striker James Beattie pulled out with a calf injury, with Moyes needing to put three untried teenagers on the bench.
Chelsea had their own problems with Eidur Gudjohnsen taken ill before the game, but Jose Mourinho was able to draft in Joe Cole and call Damien Duff onto the bench.
Everton were forced to use Phil Neville in the centre of defence and Mikel Arteta in a holding midfield role.
And they looked short of strength all over the pitch as Chelsea took almost casual control of the game, leaving Everton's midfield of Simon Davies and Leon Osman chasing as the ball was swept from one white shirt to the other and it took 15 minutes before Cudicini even touched the ball.
But David Weir and Neville held Hernan Crespo at bay and halted the darting runs of Arjen Robben.
Everton needed to up their tempo to at least make Chelsea work for their possession, and slowly the home side got themselves into the game.
Osman saw a shot deflected for a corner as Everton had a flurry of set-pieces, while Crespo saw another long-range effort saved by Nigel Martyn, making his 100th appearance for the Toffees.
Then Nuno Valente and Ferguson combined on 35 minutes to provide Kevin Kilbane with a header that was saved by Cudicini.
A minute later the same pair again linked and this time when Nuno Valente's cross came in from the left, McFadden rose to send a dipping header into the bottom corner.
Chelsea had been knocked out of their stride but countered with Robben forcing Martyn into a save at his near post with a fierce low drive soon after the break, and then Lampard's cross was headed into Martyn's arms by Cole.
Everton were furious when referee Graham Poll denied them a penalty after Cudicini had flattened McFadden with the ball largely incidental to the mid-air challenge.
The Scot took several minutes to get back to his feet and was eventually led off with blood pouring from his nose to be replaced by Gary Naysmith on 54 minutes.
Chelsea sent on Carlton Cole and Duff for Asier Del Horno and Maniche on 59 minutes before Crespo then hooked over from six yards with Everton appealing in vain for an offside flag.
Crespo was even more wasteful when Carlton Cole set him up and the striker lifted a shot wide of the far post. Chelsea were now taking the proceedings more seriously and had Everton pinned back.
The equaliser arrived soone afterwards when Robben and Gallas combined down the left and the ball was played in for Lampard to finish calmly into the bottom corner.
Everton took off Davies and sent on 17-year-old Nigerian striker Victor Anichebe for his debut, before substitute Robert Huth was booked for a foul on Ferguson in injury time.