Eden Hazard to the rescue as Chelsea force replay

Rafa's cracking up? Only with smiles. Chelsea's besieged interim first-team manager shrugged off catcalls from the Stretford End, continued baiting from his own Chelsea fans and another snub from Sir Alex Ferguson to change the course of this absorbing FA Cup quarter-final with two highly influential substitutions. Fact.

Benitez will never endear himself to Chelsea fans, following ill-considered past remarks, but he deserves praise for bringing on Eden Hazard, who swiftly scored a wonderful goal, and John Obi Mikel, who brought some resilience to a previously passive midfield. A counter-argument could be presented that Benitez should have started Hazard but at least he reacted, at least he made the right call. He is off in the summer but at least he will take the satisfaction of knowing he outwitted Ferguson here with his changes from the bench.

Suddenly, Chelsea remembered they were FA Cup holders. They fought hard, defended better, attacked more and would have won but for another reminder of the remarkable shot-stopping qualities of David de Gea, who stretched out a right boot to deny Juan Mata right at the death.

The replay date has still to be decided because of Chelsea's Europa League distractions before Manchester City learn their semi-final opponents at Wembley. If United play as powerfully as they started here, they will progress. If United play as weakly as they ended here, they will deservedly be knocked out.

It was United who faded badly here. It was United who looked like they had flown back from Bucharest late on Thursday. For the final half-hour of this tie it was Chelsea who appeared to have enjoyed 46 hours more rest-time. The way Benitez's side attacked in the second half was a reminder of what can transpire if visitors play without fear here.

For United fans, it must have been alarming to watch the life drain from their players. Jonny Evans made some important clearances, De Gea made some crucial saves, and Michael Carrick could hold his head up high for his work in midfield but too many others wilted.

Wayne Rooney was good for 45 minutes, scoring and scheming, but his influence ebbed after the break, particularly when he was again pushed wide when Robin van Persie and then Danny Welbeck came on. United's other substitute, Antonio Valencia, who had arrived in the first half when Nani hurt a hamstring, looks the shadow of the force of last season.

For almost an hour, all seemed well for Ferguson and woeful for Benitez. Both sets of supporters were still trading toxic songs about Benitez when his team fell behind. Carrick created United's first after five minutes, picking out Javier Hernandez with a drilled, 40-yard pass. Petr Cech totally misjudged the situation, rushing out, gifting space behind him which Hernandez found with a calm, accurate header.

Gary Cahill also failed to be more alive to Hernandez's movement.

Benitez had paired Cahill and David Luiz, a slight surprise with John Terry available. Seemingly a king in exile in his own domain, Terry looked on from the bench. One day Terry may write his story of his Chelsea career and his views on Benitez will surely make fascinating reading.

The afternoon worsened before it improved for Benitez. After 11 minutes, Rooney took charge of a free-kick in front of the Stretford End, whose residents were singing his name. Rooney curled in the ball which comfortably cleared the two-man wall of Victor Moses and Ashley Cole. It dropped towards a crowd of players, carrying sufficient force to carry it through Luiz's curls and continue into the net. Rooney smiled and blew a kiss to the United fans.

Chelsea attacked a bit but without real conviction. Jonny Evans blocked a Moses shot. De Gea saved from Frank Lampard. Moses then hit the corner flag, prompting the home support to ask "Are you Torres in disguise?" United were breaking occasionally, looking for a third.

Hernandez shot over. Cech saved from Rooney and then reacted athletically to push over Luiz's surreal attempted clearance. Rooney chipped the ball just over.

At the break, many expected Benitez to bring on Terry to organise the defence and push Luiz into midfield to inject some energy. Chelsea needed more direction, more invention, more belief. Benitez waited six minutes and then made his move. The sight of Lampard being withdrawn was greeted by Chelsea fans with chants of "You don't know what you're doing". The Stretford End joined in with "Rafa's cracking up".

Not here. The changes worked. Mata picked out Hazard, who wrong-footed Rafael before curling the ball past De Gea just before the hour. With Mikel anchoring, Ramires pushed on more. Within nine minutes of Hazard's goal, Chelsea equalised through Ramires. Demba Ba and Oscar combined to send Ramires into the area. He turned Evans, and placed a measured left-footed shot past De Gea and in.

Mata almost won it in the 90th minute. Luiz nicked the ball off Van Persie and lifted a fine pass to Mata, who elegantly steered the ball around Evans. Only De Gea's reflexes kept United in the Cup.

It would not be a game between such rivals without controversy. Off the ball, Ferdinand tripped Torres and pushed him in the back. The Spaniard looked totally bemused as the United centre-half pulled him back up. Ferdinand versus Torres is hardly renowned as one of English football's major blood feuds. Ferdinand's petulant act requires an explanation, probably to the FA. Howard Webb did not take any action, presumably having missed the incident, so the beaks can intervene.

A well-established enmity resurfaced. At the final whistle, Benitez marched straight to the tunnel, not even waiting for the possibility of being blanked by Ferguson. As he strode off, Benitez could have been forgiven for permitting himself a quiet smile.