The Brazil forward trained with the squad on Monday for the first time since injuring his ankle last month and the La Liga champions said he was close to a return to action.
At a news conference on Tuesday previewing the match in San Sebastian, coach Gerardo Martino would not be drawn on whether Neymar would feature against Sociedad, or whether he would return in Saturday's La Liga game at home to Rayo Vallecano or at Manchester City in next Tuesday's Champions League last 16, first leg.
"He trained well, he has no pain and physically he is in very good shape," Martino said.
"We will see what happens between tomorrow's game, the Rayo game and the Manchester game," he added.
"As I have said before, for me if there is a very important match coming up that everyone is talking about, his presence or otherwise does not have the Manchester match as the target.
"It could be before, it could be after. In any case, it will be when we consider it to be the right time and when we are taking the least risk with the player's future."
Barca, the record Cup winners, have a 2-0 lead over Sociedad from last week's first leg and if they make it through to April's final they are likely to face great rivals Real Madrid.
Real have a 3-0 advantage over city neighbours and holders Atletico Madrid, who beat them 2-1 in last season's final, before their second leg later on Tuesday.
(Writing by Iain Rogers in Madrid, editing by Toby Davis)
