Carvalho, who turns 39 in May, was rumoured to have joined the big-spending club after spending time with Villas-Boas' side at their training camp in Qatar last month, and the Portuguese coach confirmed on Monday that the deal to sign his compatriot has now been completed.

"Yes, we signed the agreement after the winter training in Qatar," said the former Chelsea and Porto boss. "He is very experienced and we can benefit a lot from that.

"Due to the change of regulations for foreign players, his playing time might be reduced but he has won so many championships in his career and it is good for us. It is a very good signing for us, though somehow we all have to obey the regulations."

The Chinese Football Association reduced the number of foreign players permitted to be fielded by clubs in the Chinese Super League from four to three last month, although clubs can still have a maximum of five in their squad so long as that number includes one player from another Asian nation.

SIPG have already signed Oscar from Chelsea for an Asian record transfer fee as well as Uzbekistan international Odil Ahmedov in the current window, and they join a squad that also features Brazilian strike duo Elkeson and Hulk.

Shanghai make their first appearance of the season on Tuesday in the ACL playoffs when they take on unfancied Sukhothai from Thailand, and Villas-Boas is confident his side can pick the win needed to secure a place in the competition's group phase, which kicks off later this month.

"We sent people to observe our opponent last week, so now we have some ideas," he said.

"We have prepared well. We had a two-week training camp in December in Shanghai, and we have had a five-week training camp after coming back from Doha. We have very good fitness preparation, and mentally too, for the forthcoming new season.

"It will be a one-match elimination tomorrow. We have the advantage of playing at home. We have to treat it very seriously from the first minute onwards, and we can't allow things like red cards.

"Our opponent has showed their quality in previous matches, I hope we can overcome them and qualify for the next round."