Ziyech agreed to join the Premier League outfit this summer after Chelsea thrashed out a €40 million agreement with the Dutch champions.
The Morocco superstar has been tipped by many to be the final piece in the jigsaw for Frank Lampard’s men, with the Blues suffering to create enough chances in the final third.
Gronkjaer has heaped praise on Ziyech and admits the 27-year-old was the standout performer in the Ajax team for the past few years.
"Ziyech was the one who has caught my eye over the past two seasons even though he wasn’t produced by Ajax's academy," the 42year-old told Goal.
“You need players like that. I think all the top clubs will have looked at Ziyech and asked the question if he is good enough for our team.”
"He is a fantastic player but I think for Chelsea he will be in the starting XI straight away.”
"Almost all the clubs in the Premier League could afford someone like Ziyech. Newcastle will be right up there competing in the market again. It is a good signing and he will start a lot.”
"Also, we still have yet to see the true potential of Christian Pulisic as well because he is going to be a great player as well. So those are things to look forward to at Chelsea."
Gronkjaer played for Ajax for two years before joining Chelsea, where he played between 2000 and 2004.
