Goals from Ante Rebic, Luka Modric and Ivan Rakitic saw Croatia pick up the victory against a dysfunctional Argentina side to put them top of Group D, while Jorge Sampaoli's side must now wait for results to go their way if they are to progress.
Ronaldo, however, single-handedly earned Portugal a point against Spain with a hat-trick in their opening game before following up with a winning goal in his side's 1-0 victory over Morocco in Matchday Two.
And former Argentina international Simeone believes that it's Ronaldo's performances amongst a 'normal team' in the Portugal national side which sees him above countryman Messi.
“Messi is very good but he is very good because he is accompanied by extraordinary players," Simeone said.
“But if you had to choose between Messi and Ronaldo for a normal team, who would you choose?”
Simeone is said to have made the comments in a WhatsApp audio message to Atletico assistant, German Burgos, which has since been leaked in Spain.
The Atletico boss also slammed the current Argentina set-up for a lack of leadership and called for some fight from the players, claiming the squad currently looks 'lost'.
“What we saw against Croatia is the picture of what has happened over the past four years unfortunately,” Simeone said. "Anarchy, no leadership from the FA or the people in charge.
“I do not see anyone leading. There is no leadership, either from the coach, who should be leading, or the players, who should be led. I see that the team is lost.
"It is clear that in the dressing room players are beating each other up but in these situations, you need someone to fight.
"We all say the players are the most important part of the game and the coach usually play it down when players mess it up, but the Coach is also participating in this.”
Sampaoli has come under heavy fire since Argentina's 3-0 defeat, having drawn their World Cup opener 1-1 with Iceland.
Messi was denied an opportunity to win the game for his side when his penalty was saved by Hannes Por Halldorsson , after Sergio Aguero had opened the scoring.
And while Sampaoli's team selection in both games have been wrong, according to Simeone, the Atletico boss believes that a spot in the last 16 is still available to Argentina.
“He picked the wrong team and tactics, too," he said. “He should have started the weaker team against Iceland, in the way he played against Croatia, because they are a much weaker team.
"And the other way round – the way he played against Iceland was how he should have played against Croatia. When the coaches screw up, it’s worse than when the players s*** it. So it has to be down to the coach. It’s on him.”
"I think it will happen. Nigeria is going to beat Iceland and there you will have the chance to beat Nigeria and pass, as long as Iceland does not win against Croatia."