The Blues have invested heavily already, with the signings of Juan Mata from Valencia, midfielder Oriol Romeu from Barcelona and striker Romelu Lukaku from Anderlecht.

The Portuguese manager has focused on adding further attacking options to his side at Stamford Bridge so far in the transfer window, but the 33-year-old was also keen to stress the need to remain focused on his team's defensive capabilities at the same time.

"It's not by bringing in extra forwards or forward-thinking players that you become more offensive," Villas-Boas said.

"Maybe in the end you are punished at the other end and you could become exposed defensively if you do."

"You just have to create a balance."

Chelsea have struggled to impress in their opening Premier League fixtures, but Villas-Boas said the games are the perfect example of the Blues trying to find consistency.

"What we are trying to achieve has reflected itself in both second halves at Stoke and against West Brom," he said.

"We are trying to find that 90-minute performance and consistent performance."

"But it takes time in the beginning because there is a radical change in the way you train and play."

The west London club remain heavily linked with Tottenham's Luka Modric and have had a bid for Porto winger Alvaro Pereira rejected, with Villas-Boas insisting he could do with further midfield options, especially with a long-term injury to Michael Essien.

"We know that we need one more number in midfield, but if it doesn't happen it's because we trust in these people," he said.

"So anything can happen but, at the moment, nothing is happening."