This is despite the Catalan club that won four out of four without an Argentine maestro.
Messi was forced after 26 minutes to win a 4: 2 victory over Sevilla, who were at the top of the table before their visit to Camp Nou last month, with a broken radial bone in their right hand.
This meant that he did not play in the group stage in the Champions League, winning at home with Inter, 5-1 from ties with Real Madrid and the last 3-2 away win at Rayo Vallecano last weekend.
But Messi returned to the full training of the first team last week and traveled with the Barca team to Italy in their opposite fight with Inter in San Siro tonight (20.00).
The head of the Barge, Ernesto Valverde, admitted: "Leo is at the point where he could be available, but we have to wait, we do not take the risk." Obviously, it is necessary to get Messi back as soon as possible. "
Along with the talisman and captain of the Catalan club, which is approaching the return, versatile Roberto admits that the 31-year-old was very misguided despite his improved form without him.
Speaking to the press yesterday, Roberto said: "Without Leo we are not so strong, but we have shown that we are a great team.
"He is happy that he is with us again and it is good for us that he traveled.
"We were scars after his absence and it's normal that it affected a band like ours.
"Fortunately, we managed to win matches without him and I do not know if he will play, but we are happy that we have him here."
Barca needed goals from Ousmane & Dembele and Luis Suarez in the last three minutes to get a nervous victory over Rayo last Saturday.
Roberto also called on Valverde to come in at the level they set against Real Madrid last weekend.
He added: "On the second day [vs Rayo] we started the game very well, but then it was hard to play like in previous matches.
"Against Inter in Milan, we have to follow the line we have taken against Real Madrid or Inter at home.
"If we win, we are the first in the group and we want to play well.
"In the last few years it has been difficult to win away from home, but at Wembley [against Tottenham] we played a great game and we hope to repeat it.
"We have to improve and be self-critical, we are calm because we are the first in the La Liga and our Champions League group, but we must improve our defense.
"All matches are important, but the tensions of matches with Real Madrid or Inter can be different.
"We know that points against Rayo are equally important in the fight for La Liga."