The Barcelona attacker missed two months of the 2013-14 campaign with a thigh injury, while he was criticised for a perceived lack of effort in the final months of the campaign.
However, Sabella is confident that his star player will be in top form for the World Cup this summer.
"I'm not worried about Messi. Far from it – he's looked good whenever I've seen him," he told Ole.
"The thing is that when a club like Barcelona, who are used to winning, lose, then people get upset Barcelona players aren't used to that sort of stuff.
"But experiences like that make you stronger. Messi is a top professional."
Messi has scored 37 times in 83 games for his country.