Sam Kerr's second-half goal proved the difference as Chelsea beat Manchester United 1-0 to win a third successive English Women's FA Cup final before a record-breaking crowd at Wembley on Sunday.

But it needed a desperate block from Chelsea goalkeeper Ann-Katrin Berger in the seventh minute of added-on time to deny United an equaliser in front of 77,390 spectators -- a world-record attendance for a domestic women's football match.

Chelsea manager Emma Hayes's decision to bring on Pernille Harder, who has been injured for much of the season, just before the hour proved a turning point in a match where United had the better of the early exchanges.

"I think it's the sign of a great team, we didn't have our best game but we pushed through," Australia striker Kerr told the BBC.

Hayes said her team's experience of big-match occasions at Wembley had served them well.

"We've played here more times than Stamford Bridge. Yes it's home."

Hayes added: "We know how to stay in a game and even if we weren't at our best we have to work out how to change it."

It took United, in their first women's FA Cup final, just 20 seconds after kick-off to put the ball into the Chelsea net only for the goal to be disallowed for offside.

Chelsea, the reigning English women's Super League champions, failed to clear Ella Toone's cross from the right and Leah Galton swept the ball in.

But the flag had gone up, with VAR confirming Toone had moved a fraction too early.

United, who only established a women's team in 2018, dominated the first half.

They almost broke the deadlock just after the half-hour when Millie Turner's deflected effort was well saved by Berger.

United went close again when Galton poked the ball over from six yards out from an Alessia Russo cross.

But three minutes before half-time, Chelsea almost punished United's failure to take their chances when Lauren James's looping header was brilliantly clawed away one-handed by United goalkeeper Mary Earps, one of the heroines of England's European Championship final-winning team at Wembley last year.

Goalless at the interval, the match turned in Chelsea's favour soon after Harder came on.

Maya Le Tissier failed to deal with a long ball and Kerr raced on to it down the left wing.

The ensuing cross found Harder, but her first touch saw the ball trapped under her foot, and a weak shot proved no problem for Earps.

Harder, however, was instrumental in Chelsea going 1-0 up in the 68th minute when her excellent low cross from out on the right found Kerr, who didn't have to break stride as she turned the ball in at the back post.

Kerr's goal meant the forward, who celebrated with her trademark back flip, had scored in three consecutive FA Cup finals.

"Sam Kerr is priceless but let's credit Pernille," said Hayes.

"We know we needed more stretching runs," added the Blues boss, who has now won 12 major trophies since taking charge of Chelsea in 2012.

United almost made it 1-1 in the very closing stages when Berger flapped at a cross, only to block Galton's shot before Chelsea cleared the danger to stay on course for another league and cup 'double'.

Afterwards, rueful United manager Marc Skinner said: "Chelsea have done hardly anything in the game, but they are winners for a reason, they find that tiny little gap."

He added: "We won't dwell on this, it fuels us. We watch this (Chelsea's celebrations), this will be us in future."