The Blues face their second leg semi-final Champions League game at Stamford Bridge with the score at 0-0.
Hiddink knows that Barcelona will be keen to score and will have looked at Chelsea's last two performances with a degree of optimism - both West Ham and Fulham did what they failed to do and score against Chelsea.
After defeating Fulham 3-1, the Dutchman revealed that while he is happy with the three points, it's the match against Barcelona which is his priority.
"We stared well," said the temporary boss of the Blues.
"We had Drogba and Anelka up front from the beginning so I can see some options which I can use in games.
"But I will not say what I will do against Barcelona.
"I wanted to see both of them in a real game.
"In Barcelona, we were forced to defend. I wanted to go forward a bit more, but you cannot blame us for defending.
"But at home, we will attack more."
It was then that Hiddink revealed his fears:"You cannot afford to have sloppy errors, " he said.
"I'm not shutting my eyes when I am not happy.
"The sloppiness is not just any one position, but it's a sequence of errors.If we do that at a high-level of European contest, you will be exposed and punished."
Fulham boss Roy Hodgson was full of praise fore the Blues and will be cheering them on against Barcelona.
"Chelsea are very good team, but they had the advantage of having a goal start on us [Chelsea scored their opener in 50 seconds].
"We got parity quickly but went a goal down again.
"When the ball was lost, it was tough to get it back.
"But we kept going.
"Chelsea will have a tougher game against Barcelona than they had against us.
"They [Barcelona] will test their defence more.
"I hope that Chelsea will follow up on their 0-0 draw in the first leg at the Camp Nou and we have two English teams, albeit with many foreign players in the final.
"As an Englishman, I'm proud to see two teams in the final and I want Chelsea to win it."
Good on you, Roy.