The Blues take on Stoke City at the Britannia Stadium having been linked with midfield targets such as Tottenham Hotspur's Luka Modric and West Ham's Scott Parker throughout the summer, but with only Oriol Romeu secured so far.
However, with Michael Essien set to miss the next six months due to injury and Yury Zhirkov having left the club, the new manager does not have a wealth of options and he admitted this could cause a problem.
"We are struggling with numbers in midfield," he explained.
"We have Oriol [Romeu] still away at the Under-20s World Cup. He'll return late in August, so numbers are short [in midfield]."
However, despite this Villas-Boas is confident that he has the versatility in the squad to cope with a lack of personnel.
"It's good enough for us that the people we have can play in those positions - we have a lot of versatility in midfield," he added.
"Florent Malouda and Yossi [Benayoun] can play number eight or number 10, and that gives us flexibility.
"That's why we're happy with the squad running into the Stoke game.
"All have been playing at a high level. In midfield, everyone has been performing well."Another player unavailable for the start of the season is forward Daniel Sturridge, who is serving a three-match ban for a red card picked up at the end of last season while on loan at Bolton Wanderers.
"It was a nasty incident so we respect the three-match ban being applied, and we can't do anything about it," Villas-Boas admitted.
"But Daniel has been showing good levels in pre-season.
"He won't be there for the next three games, and we have to accept that."
The former Porto boss did question the logic in the ruling that disallows Chelsea from making an appeal against the ban because he was a Bolton player, however, adding: "It could be in the interest of that club not to appeal because they know that player is going to return to his mother club."