henry/The Barcelona striker missed their opening game, a poor 0-0 draw with Romania, but is expected to return for Friday's game against the Netherlands.
"He's not had a great season in Spain so he wanted to show at the Euros that he's the one to count on," former France star Desailly told BBC Sport.
"The first game was not for him, for the second I'm sure he'll be ready."
Coach Raymond Domenech's team failed to impress against the Romanians and came in for criticism from some of their own fans.
But Desailly, who was a member of France's World Cup-winning team in 1998, says there is no need to panic.
"You have to be patient," he said.
"Maybe physically the players were not ready for the first game, maybe the way Domenech set up the players on the pitch he knew it was going to be a bit difficult at the beginning.
"But he has still has hopes for Henry who is coming back for the Dutch game.
"There are plenty of small details which make him confident."
Although Henry has made his name and reputation as an out-and-out striker, Desailly said this may not be the role he needs to play for France.
"The problem I have is - is he able to be a playmaker, because France need someone to run the team," he said.