Messi was stretchered off against Benfica after colliding with visiting goalkeeper Artur Moraes, but there was relief soon after with confirmation that the complaint was no worse than a bruised left knee.
The Argentina international worked in the gym as his Barca team-mates trained outside today, and Messi said he still had a chance of playing at the weekend.
"I feel fine, but I don't know yet if I will be available for Sunday," he said at a promotional event at the Nou Camp today. "I'll see. I am grateful for all the messages of support I have received."
Messi said he was hurt when he struck Moraes, but then tried to score with a curling shot before falling to the ground and clutching his knee.
"I thought it was the last shot I was going to have for a long time," he said. "So I decided to gamble and hit it."
He added: "The truth is I did not think about anything because all I could feel was the pain. But in a moment I thought the worst. When it was shown it was not a severe injury I was calmer."