The 31-year-old becomes the first Warrior to be nominated for the award since 2017, when Jonny Gray and Stuart Hogg were longlisted for the prize after helping the club reach the knockout stages for the first time.
No player has made more carries in Europe's premier club competition than Dempsey after the pool stages, the Scotland international's tally of 58 leading to 164 metres made with ball in hand.
The number eight also sits third in the tackle charts after four matches, behind only Sale Sharks back-rower Ernst van Rhyn and fellow Warrior, Matt Fagerson.
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