The champions-elect needed an 89th minute winner from Virgil van Dijk to see off the Hammers 2-1 on the day.
And afterwards, Slot admits he was left impressed by West Ham, particularly two of their players.
“That's what makes the Premier League so strong. I believe they are sixteenth or seventeenth (seventeenth), but I can name two players of them who can easily join us, if we are talking purely about quality," said Slot. “That's what the Premier League is.
“Mohammed Kudus and Lucas Paquetá were great today (Sunday), especially in the second half.
“I saw the manager (Graham Potter) of West Ham tell Kudus to play lower. From that moment on he ran everywhere and was almost impossible to keep up with for us.
“The boys had to fight hard. And I, like the fans, did everything I could to boost them from the side. We survived. ”