The Daily Mail says Shaw is attracted by the promise of regular first-team football at United and has told the Old Trafford club he will make the switch if they can agree terms with Southampton.
United have more than £100m available for transfers this summer and are ready to spend big to land Shaw ahead of the departure of current left back Patrice Evra, the 32-year-old fading France defender.
Shaw has one England cap and has been one of the stars of the Premier League season. United will offer him a starting salary of £80,000 a week.
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