After a goalless first half, Amad put the visitors ahead with an excellent strike into the top corner.
Substitute Alex Pritchard then added a second before Jack Clarke completed the scoring with a low effort.
After Millwall failed to beat Blackburn, Sunderland moved into the top six and will now face Luton in the play-offs.
Here’s how Phil Smith rated the Sunderland players against Preston:
After Millwall failed to beat Blackburn, Sunderland moved into the top six and will now face Luton in the play-offs.
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