Chelsea announced they had agreed a £36m deal for the Moroccan attacker all the way back in February, though he suffered an injury before the start of the season which has hampered his involvement.
After cameos off the bench against Southampton and Manchester United, Ziyech made his first Premier League start at Turf Moor and showed exactly why Chelsea brought him to west London.
The 27-year-old opened the scoring with a fine finish from the edge of the area before later setting up Timo Werner with a perfect through-ball and Lampard believes he will be a massive player for Chelsea going forward.
Asked about Ziyech, Lampard said: ‘Yeah really impressed, really excited.
‘I knew the quality, but to see him first-hand at the training ground it was so frustrating that he got injured because I could see it.
‘But his personality, his work rate off the ball – which I think some people might expect a winger with his technical qualities to not have a work ethic for the team – he has that.
Expanding further in his post-match press conference, he continued: ‘I expected a lot of him, because I was very aware of his quality, that’s why we brought him to the club.
‘I think I’ve said it a bit now, but he brings a different quality to us with his eye for a pass, receiving, his crossing and everything, his assist-making.
‘But what I’ve seen since he’s been here as well is his absolute personality when he plays to want the ball. His work rate off the ball is very, very good as well.
‘And he’s brought those qualities and he’s come in with a real confidence. He’s definitely given us a big boost with his demeanour and the way he plays. Two games in a few days, with a trip to Russia in between, for him, after being out for so long, it’s been a really good start for him.’