Frank Lampard made Morocco international Ziyech and Germany striker Werner his first and second signings as Chelsea manager and both impressed in the club’s pre-season friendly against Brighton on Saturday.
Ziyech arrived at Stamford Bridge having developed into one of Ajax’s most important players, while Werner scored 95 goals in 159 appearances for his former club RB Leipzig.
But despite their obvious talent, Hasselbaink says Werner and Ziyech may need ‘six months’ to settle in at Chelsea and begin to flourish in the Premier League.
‘German football is totally different to the English game so it will be difficult for Timo Werner to settle straight in,’ the former Chelsea star told GentingBet.
‘We know he’s a talented player. We know what he can do. And Chelsea need a player that can score goals.
‘But, we also need to give him the time. If you look at [Arsenal star Pierre-Emerick] Aubameyang when he came, he needed six months. So, give him those six months as well.’
On Ziyech, Hasselbaink added: ‘He is very creative, has an excellent left foot, is very good at set pieces and I expect a lot of assists from him.
‘He’s got that aura around him in that he wants the ball. He wants that responsibility, he’s not afraid to score goals.
‘But he is a silky, beautiful player and something that Chelsea don’t have – a midfielder with a left foot who can bring something different.’
Chelsea begin the 2020-21 Premier League campaign on September 14 with a trip to Brighton.