Chelsea manager Avram Grant was quick to praise Barnsley after the FA Cup holders crashed to an amazing sixth round defeat at the Championship side.
However, the Blues boss was unhappy with the state of the Oakwell pitch which he believed contributed to his side's 1-0 defeat.
He said: "It's a big disappointment. It's a quarter-final and we lost.
"First of all I need to congratulate Barnsley. They played very well today and showed good spirit.
"For us it's not a pitch we can play quality football on. It was not good in the first half and the second half we started very well.
"We played quick, we created a lot of chances and then, like it happens sometimes in football, we conceded a goal and we couldn't score.
"I don't think we thought this was an easy game. We knew they beat Liverpool away, so we knew what to expect.
"I wanted both (Lampard and Drogba) to play, but they were injured, so they couldn't, but we played with a team that was good enough to win the game.
"I don't know if I'm shocked, but I'm very disappointed. You can say so yes, since I came to Chelsea, this is the most disappointing day."