Celtic were beaten narrowly by both Milan and Barca and although Ajax are expected to come third in the group MacLeod sees a lot of quality in their team.
"People are thinking Ajax will be third best of the three but sometimes when you know the opposition [it is different]," Sky Sports News quotes MacLeod as saying. "Celtic knew Barcelona and they handled them really well.
"Whereas Ajax will be fresh, they will be looking forward to playing here in a fantastic atmosphere, so they will possibly play as well as the other two teams.
"They have always been one of the top European clubs but I think people are looking at them and thinking that they are maybe the weakest one in the group."
Celtic take on Ajax at Celtic Park on October 22.