The Czech international has now conceded seven goals in just two games – both at home – and will be under further scrutiny ahead of Saturday's FA Cup semi-final against Arsenal at Wembley.
Asked whether the 26-year-old was suffering problems, Hiddink replied: "That's true. He is very intelligent and self-critical, and wasn't happy with his performance against Bolton [last Saturday]. Always, even when he has an almost perfect game.
"He knows he had a difficult time against Bolton, but also tonight.
"You could see he wasn't at full confidence. When it's a goalkeeper, it can have repercussions in goals. But he will stay a very good goalkeeper."
With Carlo Cudicini having departed for Tottenham in January, Cech's understudy is the unconvincing Henrique Hilario. Hiddink refused to confirm, however, that Cech would play against Arsenal, simply stating:
"Every person has this small period of not being in top form. We'll think [about the FA Cup semi-final]. He knows himself, and the line-up will be made on Saturday … it's not always a reason to replace someone."
With Didier Drogba admitting that Chelsea had "lost their nerve" in the first half of a match of rare drama and exhilarating fluctuations, Hiddink must consider whether Cech's own lack of confidence is undermining his team. "The three goals we conceded on Saturday were still in our
head, so that's why we were a bit in between," Drogba said.
No one more so than Cech. Hiddink said he had feared the alarm bells. What he got, for a while, was the mental shock equivalent of one of those old-fashioned klaxons placed about an inch from his ear and blown with full force. And it came courtesy of a clanger by Cech.
Margins of error are slight in professional sport. At this rarefied level they are even slighter. About one step in fact – which is all that Cech took, forward, towards where he expected the ball to be aimed as Fabio Aurelio prepared to take a free-kick. It was all the Brazilian needed.
Quick-witted, sure, and his effort was struck strongly enough but it still should not have beaten a goalkeeper of Cech's calibre.
Except, this season, that calibre has been called into question. There were other errors and nerves and whichever way it is cut, conceding four goals at home is a bad night for any goalkeeper, even if his mistakes set the tone, with Pepe Reina also far from infallible.
Cech has endured a difficult season – partly through his frustration at the coaching, or lack of, administered by Hiddink's predecessor, Luiz Felipe Scolari. The feeling is that he simply is not the great goalkeeper he was prior to the horrific injury inflicted on him in October 2006 when he was kneed in the head by Reading's Stephen Hunt and suffered a fractured skull in an incident that threatened not just his career, but his life.
Still Chelsea prevailed last night and Cech, like the rest of his team, showed what Frank Lampard termed as "character". "We didn't turn up in the first half, Lampard said. "We didn't approach the game in the right way, maybe we thought we were almost through – even though we kept telling ourselves we weren't. But our character in turning it around at half-time says a lot about the players and we need to carry on like that."