The Dutch coach is convinced, however, that last season's player of the year Eden Hazard will stay, despite recent transfer speculation linking him to Paris St Germain and Real Madrid.
"He's very keen to be here, he's happy here, his family's happy here and he recently extended his contract," Hiddink told a news conference.
The experienced Dutch manager added that Hazard knew he had to improve to recapture the standards that led to him being voted the Premier League's outstanding player by his peers a year ago.
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The Belgium international netted 19 club goals in all competitions last season, but has scored only once for Chelsea this campaign, a penalty against second-tier Milton Keynes Dons.
"He has to step up, he knows that," Hiddink said ahead of Chelsea's FA Cup fifth round tie at home to Manchester City on Sunday.
"Every now and then we have a small conversation about him having to step up to the next level and I hope he will as soon as possible."
Asked about his own future, Hiddink, who became interim manager after Jose Mourinho was sacked in December, said he had no intention of changing his mind about stepping down at the end of the season.
"What we agreed, we stick to that," he said.
(Reporting by Steve Tongue; editing by Toby Davis)
