Thiago has been a target for United for the past three years now, and reports in Spain now suggest his arrival at Old Trafford is imminent.
It is understood that David Moyes has already thrashed out a ?5million-a-year contract with the midfielder that will run until 2018, with just a fee left to be agreed upon.
United believe that is a mere formality, with the player having a ?17million release clause after failing to make first-team appearances in 60 per cent of matches last season.
Talks are expected to continue over the weekend, but the expectation is that Thiago will become the first signing of the Moyes era in a notable coup for the club.
The pass-master youngster is widely considered one of the best young players in the world, but has grown impatient with life at the Nou Camp after falling down the pecking order.
And after admitting this week that he needs to be playing first-team football in order to make the Spain squad for next year's World Cup, Thiago is said to have pushed for a switch to United.