Donny Van De Beek's first-half goal means Spurs must score in Amsterdam to stand any chance.
Gullit says they must be so much better going forward if they want to remain in the Champions League.
He said on beIN Sports: "Ajax were under pressure but even under pressure they could hold their defence. They didn't give away a chance.
"But, for me, a lot of players were disappointing because I see them every week in the Premier League.
"Dele Alli, oh my god, technical wise so bad. (Victor) Wanyama, my God, technical wise, (Danny) Rose too.
"Like I said I see them every week and how is it possible to make so many mistakes.
"I know you're under pressure but you need to know what to do and they didn't."