Ziyech finally made his debut for Chelsea when he came on for the last 18 minutes in Chelsea’s 3-3 draw against Southampton at Stamford Bridge on Saturday.
The winger missed the start of the season due to injury and played just one game for Morocco before his debut at the weekend; Gullit conceded that the Algerian looked off the pace.
But the former Chelsea manager feels Ziyech’s lengthy injury layoff and his lack of match fitness must be taken into consideration before judging his cameo performance.
The Dutchman also stressed that Chelsea play a very different style of football and thinks the former Ajax man will need time to get used to it at Stamford Bridge.
“In terms of pace, it took some getting used to”, Gullit said on Dutch broadcaster Ziggo Sport.
“The balls were just taken from him.
“Anyway, he has also been injured and has only played one game with Morocco. He did well in that.
“It is just a very different style of football at Chelsea and he has joined a team who are not in form.
“Give him time.”
It remains to be seen whether Ziyech gets a start when Chelsea host Sevilla in the Champions League on Tuesday night.