The 20-year-old has joined on a Standard Loan until the end of the 2016/17 campaign.





Blues boss Zola had been looking to sign an additional frontman, following the news that the injured Clayton Donaldson is not going to available until at least mid-March.





Blues fought off interest from several other Championship clubs to secure the services of the highly-rated former Liverpool striker.





Birmingham-born Sinclair joined Watford last summer after failing to agree a new deal with the Reds.





Because he came through the ranks at Liverpool, Watford were forced to pay an agreed compensation package of a reported £4m.





During his time at Anfield the former England Under-17 international became the youngest ever debutant for the club, when he made his debut at the age of just 16 years and six days old.





Since making the switch to Vicarage Road, Sinclair has made six appearances, the most recent of which was last weekend in the FA Cup, when the Premier League outfit lost 1-0 away at Millwall.





Sinclair was not signed in time for tonight's home game against Reading, but will be available for the visit of Fulham on Saturday.





Speaking yesterday about his interest in Sinclair, Zola said: "He is an interesting player, he has potential.





"He would obviously bring pace because he is quick and has energy, but also technically he has good ability.





"He is the type of player that could certainly help us."





Sinclair will wear the number 48 shirt during his time with Blues.



