They became overwhelming favourites the moment Manchester United were controversially eliminated by a battling Portsmouth side.
However, while United could perhaps take solace in ill fortune, Chelsea simply were not good enough this evening as a single goal from Kayodo Odejayi late on was enough to seal Barnsley's miraculous semi-final berth.
Speaking to Setanta Sports after the game, the Israeli boss was honest in his assessment of the day's events: "[This is] the worst day since I'm here.
"I am very very disappointed, very sad about this. It's an important competition.
“We had a chance to do something in this competition and we didn't do it.
"Always you can say it's a case of attitude, but we know it's not easy to play in this pitch. And we didn't play well, especially in the first half.”
In a sporting manner, the former director of football also gave his best wishes to Barnsley, who have now sensationally eliminated Liverpool and Chelsea in successive rounds and will now go into a semi-final fixture at Wembley against one of Portsmouth, Bristol Rovers, West Brom, Middlesbrough or Cardiff.
"All credit to Barnsley," declared Grant. "They showed a lot of spirit. They won against Liverpool. They won against us and I congratulate them."
