Argentina have won all four of their matches by a single goal and they needed an 118th-minute winner from Angel Di Maria to beat unfancied Switzerland in the second round.
Sabella has faced accusations that he is too reliant on Messi, who has scored four of Argentina's seven goals and has provided the team with one assist.
"It seems to me that Argentina today has no idea," the 1986 World Cup-winner told Spanish newspaper AS.
"In the first half against Switzerland the team did not have one chance.
"My team were a lot more offensive than this one.
"It looks bleak for us if I'm honest.
"I wish the team played differently, that it exploited all the ability its players have.
"We haven't seen the best from them neither tactically nor individually and this worries me.
"Watching the match against Switzerland, I was alarmed that Higuain didn't have enough forward movement, that he moved inside the central midfielders. I was worried about (Fernando) Gago's tiredness, that (Javier) Mascherano had to cover all the ground.
"This was a stuttering Argentina. It needs to change its rhythm."
Speaking before Maradona's comments were published, Sabella insisted he was not over-reliant on Messi.
"The goal the other day was a ball won by (Rodrigo) Palacio - a forward playing as a midfielder," the Argentina coach told a press conference in Brasilia, where the quarter-final takes place on Saturday afternoon.
"He gave it to Messi and Messi received it in a good position, which allowed him to pass the ball to Di Maria.
"Four years ago he was criticised for not playing well and now you say we depend on him. It's not easy."
Switzerland would have gone ahead against Argentina early on in Sao Paulo had Josip Drmic not fluffed an easy chance in the first half.
And earlier in the tournament, Argentina needed an injury-time winner from Messi to defeat Iran, who are 43rd in the FIFA rankings.
Belgium possess some of the best players in the Barclays Premier League, so Sabella knows his men will have to put on their best performance of the tournament so far to progress to a semi-final meeting with either Holland or Costa Rica.
"We have not peaked yet," Sabella added.
"We have had very tight results, so we are looking for an improvement."
The Argentina coach suggested that expectations are too high in his homeland, but he conceded that a quarter-final exit would not be good enough.
"It would be a frustration if we didn't make the semi-finals, but we have hope, faith and confidence we will progress," the 59-year-old said.
"If you win you are a phenomenon and if you lose you are useless, but let's see if we can cross that line."
Argentina missed Aguero badly against Switzerland.
The Manchester City striker is making decent progress in his return from a muscle injury and he could feature against Belgium - albeit off the bench.
"He is doing quite well," Sabella said.
"We will see how he responds to the training session and then decide whether he will be part of the bench."
- Sports & Recreation
- Lionel Messi
- Angel Di Maria