Messi was taken off at half-time during last week’s 1-1 draw in the first leg with a thigh injury and missed the Catalans’ 1-0 win away to Malaga on Sunday which moved them back to the top of La Liga.
However, the Argentine took a full part in training on Monday with those who hadn’t been involved in the Malaga game as the majority of his colleagues underwent a recovery session.
“We have two days to make a decision, but with the information that I have today we are very happy with how he is recovering,” Barcelona boss Gerardo Martino told reporters after Sunday’s game.
However, Martino indicated that Neymar could once miss out from the start despite shining in cameo appearances as a substitute in Barcelona’s last two games.
The Brazilian scored his first Barcelona goal to rescue a draw for Martino’s men in the first leg and again looked like the visitors most dangerous outlet when he replaced Pedro with half an hour to go at La Rosaleda at the weekend.
“Neymar is improving all the time, you can already see the difference in him between the last two matches and the first one against Levante.
“I don’t know when exactly we will start him but you can see mentally he is ready and we will do it at the most opportune time.”
Even if Messi and Neymar don’t start, Martino will make a couple of changes to the side that started against Malaga as Sergio Busquets and Dani Alves will return after being rested in place of Alex Song and Adriano, who is also struggling with a hamstring injury.
Despite the fact that Barcelona have set the early pace in La Liga, Atleti’s start to the season has been arguably even more impressive as they followed up a 3-1 success at Sevilla on the opening weekend of the season with a 5-0 thrashing of Rayo Vallecano on Sunday to move into second.
Manager Diego Simeone has repeatedly downplayed his side’s chances of competing with Barcelona and Real Madrid for the title this season, but believes their record of winning three trophies in little over a year shows they have what it takes to go the Camp Nou and lift the club’s first Super Cup since 1985.
“The tie is still alive and we now have a big game at their place,” he said.
“I still think the league can only be won by two teams, there are so many games it is almost impossible, but we are talking about a tie over two games and we have shown we can compete in finals.”
Simeone is expected to name the same side that started in the first leg with former Barcelona favourite David Villa and the on-form Diego Costa entrusted with the task of exploiting a defence that has looked far from solid in the opening week of the season despite keeping two clean sheets in three games.