Argentina coach Alejandro Sabella has played down rumors of a rift with Lionel Messi ahead of Saturday's World Cup Group F clash against Iran.

The forward told media during the week that he preferred a 4-3-3 formation to the 5-3-2 system used by Sabella early in the Albiceleste's 2-1 victory over Bosnia-Herzegovina last Sunday.

But Sabella insisted Messi had been "respectful" and that his players were free to express their opinion.

"I wasn't annoyed at all by Leo's comments," the 59-year-old coach said. "He was asked how he likes playing and he replied. He was very respectful."

"Messi has always said this, it's nothing new. He has always said he prefers to play 4-3-3 with [Angel] Di Maria pushing forward.

"We live in a climate of freedom. I have complete trust in my players and they are free to express their opinions."

After a lethargic start against Bosnia-Herzegovina, Argentina looked a different team in the second half following the introduction of striker Gonzalo Higuain.

Less isolated, Messi became more involved and put his stamp on the match by lashing in his first World Cup goal in eight years.

Argentina can all but guarantee their passage to the knockout phase Saturday while Iran must win to remain alive in the tournament.