The same day he was named in the England World Cup squad, Shaw is also on the brink of completing the transfer to Old Trafford.
The deal is expected to be announced before the tournament in Brazil.
Despite finishing seventh in the Premier League this season, United are confident they have won the race for the 18-year-old left back ahead of Manchester City and Chelsea.
Shaw expects to get first-team football at Old Trafford and that clinched the deal, even though United have yet to name their new manager.
A powerful attacking asset, Shaw will replace France defender Patrice Evra.
United are eager to make up for their errors last summer, when they were clumsy in the transfer market, and believe this will send out a message as they start to rebuild.
The transfer will lead to the break-up of the Southampton team with midfielder Adam Lallana expected to join Liverpool and manager Mauricio Pochettino a target for Tottenham.
Written by Steve Milne
