Holland suffered a shock defeat against Denmark at the weekend and defeat against Germany will see them return home much earlier than expected.
Gullit, writing on Laureus.com, says: "Holland against Germany is always an important game but now it's even more vital. If Holland don't win, it's all over.
"I was concerned after Denmark had scored. Instead of pushing them back and looking like getting an equaliser, the Dutch failed to put any pressure on them. It allowed the Danes to gain in confidence and get better and better and that has to be a major concern.
"It looked to me as if our defensive midfielders were going backwards when they needed to be pushing forward.
"When Holland eventually made a substitution, nothing much changed and the team still failed to put pressure on Denmark. That comes down to the quality of the Dutch squad, something that was spoken about before the tournament.
"For me, the lack of strength in depth is a major worry ahead of the Germany game but I do expect there to be some changes to the team," he adds.
Gullit, who played 66 times for Holland, says in his Euro 2012 Blog that Germany do have weaknesses that Holland could exploit: "Germany had a difficult game against Portugal, remember, but they were patient and in the end it was a great victory for them.
"Despite their win, Germany did look vulnerable at the back. Portugal got through the German defence on a number of occasions and had some great opportunities but didn't take them. Portugal's openings give us hope and it's going to be a very interesting game in Kharkiv but I'm not too confident."
Gullit, who played for AC Milan and Sampdoria in Italy and played for and coached Chelsea and Newcastle in England, also fears for Russia despite their 4-1 win over the Czech Republic in the opening games.
He adds: "Russia had the standout result of the first round of games and I hope they last, but they tend to start strongly and then run out of energy as the tournament goes on."