Barca go into the match – featuring two teams with six points from their opening two Group B games – without their talisman after he suffered a broken bone in his arm in Saturday’s win over Sevilla.
Ex-Barca striker Hristo Stoichkov joked that he was available during Tuesday’s press conference, and was told to “stay close” as Valverde was willing to think about it.
But while an appearance for the 52-year-old Bulgarian can probably be ruled out, Valverde suggested he may change Barca’s shape and look to surprise Inter.
“Of course it changes things for us, but it is a challenge for us to cover for him,” Valverde said.
“We have important matches and we are excited to play them, even without Leo, as we will miss him.
“I’m looking at several options, several players who can play in that position or we could change the system. Everyone is speculating, I would guess the opposing coach too, but I’m not going to give him a clue.”
Messi is expected to miss three weeks with the injury, which he suffered in Saturday’s win over Sevilla.
Inter coach Luciano Spalletti did not want to say Messi’s absence automatically gives his team an advantage.
“It is not easy to change the attitude of a team just because of the absence of one player,” he said.
“Messi is an exceptional player, because when you think you have seen everything in football he comes and shows you something else.
“But Barcelona remain a team that do not chase the ball, who know where they want to pass and have the quality to find solutions for every opponent.
“It’s hard to imagine what Valverde will do, he has players with different qualities.”
“Barcelona have talent in every part of the pitch, this is a game against one of the strongest teams in the world.
“We must play with great confidence but the minimum of arrogance given the good spell we are going through.”
Inter have won their last seven games in all competitions, and will provide a stern test of a Barcelona side who had been winless in four domestic matches before Saturday’s 4-2 win over Sevilla.
It is six games since Barca last kept a clean sheet – a 4-0 rout of PSV Eindhoven in their Champions League opener – and the defence has come under scrutiny amid the poor run.
“In the end there is always talk about the defence and the goalkeeper, but for me it’s the whole team,” Barca left-back Jordi Alba said.
“It’s a bigger issue, it’s not about individual players. Many of us have to fix things. Things go in streaks. I think we are doing a good job, but there are many things we need to improve.”