The Markham darter refused to bow out without a fight as he fought back from 7-3 down in the best of 19 legs clash.
Pre-tournament favourite Price grabbed the lead in the match at Coventry’s Ricoh Arena as he edged 8-7 ahead.
But Aspinall reeled off three legs in a row to book his spot in the quarter-finals.
Nathan Aspinall sends back-to-back reigning Champion Gerwyn Price out of the 2020 @BoyleSports Grand Slam of Darts!
A truly incredible match as The Asp clinches it 10-8 to reach the Quarter-Finals
You can see what that means to him… what a game 🔥 pic.twitter.com/yzAIKc6DVw
— PDC Darts (@OfficialPDC) November 21, 2020
Price was bidding to emulate Michael van Gerwen and Phil Taylor who had both won the Grand Slam title three years in a row.
But there was no victory this time for Price, who had survived match darts in two of his three group games to triumph, as his 14-match unbeaten run at the tournament was ended.