EXCLUSIVE | By Manchester correspondent Alex Stevens

Louis van Gaal has been left ‘dismayed’ after seeing Manchester United lose out to Chelsea on the deal to sign Pedro, Football Insider sources understand.

The Spain international has passed a medical at the London club and will be confirmed on Thursday as their new £21.2million signing in a deal that has stunned football.

It is a huge blow to United, who had been working on a deal to entice Pedro from Barcelona for a month. Executive vice-chairman Ed Woodward was in Catalonia on Monday to put the finishing touches to the transfer and seal United’s year-long pursuit of the 27-year-old forward.

Sources have told Football Insider that Van Gaal is privately “dismayed” at his club simultaneously losing out on Pedro and for the player to then join title rivals Chelsea.

He is understood to regard it as a ‘significant blow’ to his hopes of building a team that can wrest the Premier League trophy from Jose Mourinho this season.

It is the latest in a series of the failures of Woodward-led United to push through major transfers, with Gareth Bale, Cesc Fabregas, Sergio Ramos, Arjen Robben and Thiago Alcantara among those who have slipped through the net over the last three summer windows.

United were briefing on Wednesday, as it became apparent that the Spaniard was moving to Stamford Bridge, that Van Gaal went cold on the Pedro transfer after United’s early matches had demonstrated to him they were well stocked in the wide forward position, the role in which the player is used for club and country.

This stance flies in the face of logic, with Wayne Rooney the only established striker in Van Gaal’s squad following the exits of Robin van Persie and Radamel Falcao earlier this summer.

It also does not explain why Woodward was in Spain on Monday to sign a player who the manager had long ago identified as the pacy, proven option he needed to reinforce his forward line.

United are now working on a deal to sign Sadio Mane from Southampton although the south coast club have slapped a £30million valuation on the Senegal winger.

Van Gaal is now running out of time to strengthen his squad, with just 11 days left before the transfer window deadline.

Chelsea’s swoop for Pedro came after the team’s worst start to the Premier League season in 17 years and Mourinho made it clear to the hierarchy that he wanted his forward line to be strengthened.

The Premier League champions have agreed a five-year contract with the player, which is believed to be on the same terms as the £190,000-a-week deal he had agreed with United.

But just as the Pedro transfer to Old Trafford was close, Chelsea have hijacked the move and will complete their fourth major signing of the summer following the captures of Asmir Begovic, Radamel Falcao and Baba Rahman.