The Barcelona superstar was hugely impressed with the Bhoys fans when the two clubs met earlier in the Champions League.
Messi says he'd love to see Celtic advance when they take on Spartak at Parkhead.
"The Celtic fans deserve to be in Europe," Messi said. "They have been amazing in both games we have played against them.
"We knew what they were going to be like in Glasgow. But the way they were in Barcelona after they had just lost in the way they did was amazing.
"I have never seen anything like that before. We have not always been supportive of the way that Celtic play football.
"However, their fans deserve the knockout stages. I think the competition would be a quieter place without them."
Ireland international Aiden McGeady could miss out. Spartak today said the winger was still a major injury doubt for the game.