Courtois, 19, is expected to complete his £8m move from Genk this week, becoming the first player to arrive since Villas-Boas took charge last month.
The Portuguese is not finished there, with Tottenham playmaker Luka Modric still on his shopping list and a replacement sought for injured midfielder Michael Essien.
Another highly-rated Belgian youngster, 18-year-old Anderlecht striker Romelu Lukaku, is also on the Blues’ radar, although there is competition for his signature.
However Villas-Boas, whose team beat Portsmouth 1-0 on Saturday in his first match in charge, insists he has no desire to impose drastic changes on a side that finished second in the Premier League last season.
“I think it is pretty obvious that we will go into the market at one time or the other but not with radical changes to the team. The team will keep itself [together] and most of the players,” he said.
“I am still evaluating things at the moment. It is not that I have to change things radically and I will take it step by step.” Chelsea jet out to Asia this week for a four-match tour, during which Villas-Boas hopes to firm up his plans for the squad.
The former Porto boss would like to have any signings sewn up by early August, a week before the new league season begins, but admits he could make late swoops nearer the 31 August transfer deadline.
He added: “The market always gets very frenetic in the last days and you never know what will happen.”
Villas-Boas is at pains to praise England Under-21 striker Daniel Sturridge, who shone on loan at Bolton last season, but is still pondering whether to send him away for another spell.
“This is one of the decisions we have to take,” he said.
Chelsea look to have missed out on one long-term target in Brazil forward Neymar, who is set to join Real Madrid for £40m, although his agent said yesterday that Barcelona had made a rival offer.