The Catalan club had concerns their Argentinian talisman would be forced to sit out Gerardo Martino's first league match as Barca boss due to a quadriceps injury.
However, Messi - alongside goalkeeper Victor Valdes and full-back Dani Alves, who had all trained separately on Thursday - practised normally along with the rest of the squad 24 hours later.
The fitness of the first-team trio, and Messi in particular, will be a huge boost for Martino as he bids to make an instant impact at the Nou Camp following his appointment as manager last month.
Neymar will be pushing for his competitive debut for Barca after his big-money move from Santos over the summer and while his arrival creates competition, fellow forward Pedro Rodriguez has welcomed the Brazilian's presence.
"I'm calm about it," he told www.fcbarcelona.com. "Every year I'll face competition in attack and Neymar's arrival is a pleasure.
"He's one of the best players in the world. I've had to face competition every season and it's hard to get a game. We're all working hard to get into the starting XI.
"(Neymar) will help us to unsettle defences and get goals. Those are his best weapons - he can score lots of goals.
"He's very dangerous and I am sure he and Messi will understand each other - I can tell that from training. He'll bring us a lot of joy."
Levante have lost all eight of their previous league visits to Barca stretching back to 1964 but the Valencia-based side came agonisingly close to claiming their first point at the Nou Camp last season.
On that occasion Levante were six minutes away from holding Barca to a goalless draw only for Cesc Fabregas to pop up and net the only goal of the game.
Although they were left empty-handed in the end, Levante defender Pedro Lopez believe his side should be looking at that match as a guideline for Sunday's trip.
He said: "The game against Barca will be difficult. They are the best team in the world and at their ground it will be complicated, but the model we have to look at is that of last season's game. We were united, very good defensively and always in the game."
Lopez also dismissed suggestions the Barca players might be suffering from fatigue following their pre-season tour to the far east and the fact a number of Martino's squad were involved in international action in midweek.
"Of those who say that Barca are tired, I honestly don't think so. They are a great team," he added.
New Levante coach Joaquin Caparros, who took charge in June after replacing Juan Ignacio Martinez, has a doubt over the fitness of midfielder Pape Diop while Christian Lell and Aloys Nong have also been battling knocks.