Emma Hayes has branded Kadeisha Buchanan's dismissal during Chelsea's Champions League semi-final defeat to Barcelona as the "worst decision in UEFA Women's Champions League history".

The Blues crashed out of the competition after a 2-0 second-leg defeat at Stamford Bridge, having won the first-leg in Catalonia 1-0 last weekend. Aitana Bonmati's deflected strike and a well-taken penalty from Fridolina Rolfo saw the visitors advance to the last four, where they will take on either Lyon or Paris Saint-Germain in Bilbao next month.

But it was referee Iuliana Demetrescu's decision to issue Buchanan a second yellow card that Hayes believes had the biggest impact on the tie. "I was surprised when (Demetrescu) was selected as she’s known for easy yellow cards," she said in her post-match press conference.

"I thought that was the worst decision in UEFA Women's Champions League history. I’m gutted for (the players). We were robbed."

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She continued: "When you lose football matches and you've been beaten by the better team 11 versus 11... listen they're the best team in the world and they had a strong first half. In the second half it felt we were just coming on top.

"You could see the combinations, the crowd and the players were driving us and they felt really confident and so when you get such a shocking decision there's nothing you can do about it. It's hard with 11 (players) but with 10 it's virtually impossible.

"I didn't think it was a foul, let alone a yellow card. We didn't we got the opportunity to lose (the game). That was taken away."

Reflecting on the standard of officiating in the competition, Hayes added: "That's the hardest part. I stood there and looked at the fourth official and I said "surely that will be checked" but she said "we can't with a yellow".

"The toughest thing to take is that we didn't lose it. There's nothing you can do when there's such a terrible decision and it's already hard enough. They are a top team.

"When you work so hard for days, weeks, months, years, you come here and you expect the best from the officials at the very least and it feels really, really hard to take."

All of this season's UEFA Women's Champions League fixtures are broadcast live DAZN and you can register for free here. The second leg of Lyon vs PSG is also free to watch here.