Watford have snapped up Birmingham City full-back Mathew Sadler for an initial fee of £750,000.
Sadler has signed a three-and-a-half year contract at Vicarage Road and the deal could eventually cost £900,000.
Birmingham have also inserted a sell-on clause into the agreement for Sadler, who made over 60 appearances during his St Andrews career.
He had featured five times in the Premier League this season, but has been allowed to move on by Blues boss Alex McLeish.
The recent capture of David Murphy merely intensified the competition for the left-back berth at the Premier League strugglers.
Sadler, 22, will now hope to secure a regular spot in Adrian Boothroyd's side as Watford push for an immediate return to the top flight.