The Daily Star says Byram, 20, has emerged as one of the brightest talents outside the top flight after bursting onto the scene with Leeds.
Now it has emerged he is a wanted man, with the Saints leading the chase to lure Byram to the Premier League.
The Saints have had a £4.5m bid rejected by Leeds owner Massimo Cellino, while the Black Cats have also seen a similar offer turned down.
But Cellino might have no choice but to cash-in on the England U20 international and sell him to the highest bidder.
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