Ezequiel Garay, Oleg Shatov and Anatoliy Tymoshchuk are all in contention to feature in the first leg in Spain on Thursday.
That is good news for Zenit, who will be without suspended quartet Hulk, Danny, Igor Smolnikov and Domenico Criscito.
"In reality, we aren't as unfortunate as UEFA says - I don't know how many injuries they said we have, but we do have four players out," Villas-Boas told a news conference on Wednesday.
"Some didn't play in the last match because we didn't want to risk an injury, like Garay, Shatov and Tymoshchuk - they're at about 90 per cent, so now they'll train and tomorrow they'll be available to play.
"The four players out are obviously important, although the squad is big and in good shape, and we are confident that those players will be able to help us in the second leg at home.
"Obviously it's important to get a good result in this first match, and that'll be the most difficult thing about tomorrow.
"This stadium is known for it's atmosphere, but so is Petrovsky Stadium and that's why we want to get a good result, so we can go to the next phase."
