That’s what Barca boss Ernesto Valverde has said.
Valverde revealed the Argentine needed several days to recover after the challenge but was adamant his superstar is ready for the return leg in the Nou Camp tonight (8pm).
“He was okay a couple of days after it,” Valverde said.
“But he was a little bit stunned at the time.
“Although he’s okay now for this game and ready to go.”
The 31-year-old played his part in the Catalan giants’ opening goal in the first leg.
Messi floated over a cross which Luis Suarez headed back across the goal and as the ball was travelling across the six-yard box it deflected off Luke Shaw and into the net, giving Barca the lead.
It was later in the game that the challenge from Smalling took place and at the time it appeared to affect the four-time Ballon d’Or winner, as he had little impact on the rest of the game.
However, Valverde insisted Messi isn’t concerned about it happening in the second leg.
“I don’t think he is worried about the same thing happening again,” he said.
“He is fine, he is perfectly fine after the blow he suffered.”
Messi was one of a number of stars Valverde left out of his squad as Barcelona faced Huesca in La Liga on Saturday.
Valverde admitted he is unsure about who Ole Gunnar Solskjaer is going to play in Barcelona, but is wary of the threat Man Utd pose on the counter attack.
“I don’t know what the team of United’s is going to do, but we do know that we have examples of what they have done in the Champions League away from home this season,” he added.
“Manchester United have a special thing. They won a European Cup in the last few minutes (in 1999) – so we have to keep that in mind.
“We know that our rival can go on the counter attack, so we cannot allow that. What I fear most is the spirit that they have.
“We respect them as a team for what they are and the history they have. You can feel their spirit on the pitch and we expect to see that here.”