The Daily Star says the two clubs have opened talks and agreed a fee for the highly-rated teenager, who helped Crewe win promotion to League One last weekend.
The deal, rising to £6m depending on appearances and future England caps, could be confirmed before the end of this week if Powell agrees personal terms.
Crewe chairman John Bowler said: "There is a time when it is right for players to move on and Nick is at the front of that queue.
"We need to gauge what is right for us in terms of value and what is right for the player. We have a lot of investment in the lad.
"For him to go on and play Premier League football says a lot about our academy and Crewe Alexandra."