A Patrick Mahomes rookie card just sold for over $4 MILLION ... and the price tag was so staggering, even the NFL star himself couldn't believe it!!!
PWCC Marketplace announced the sale Wednesday ... saying the deal officially makes the piece the most expensive football card ever.
And, Mahomes was blown away by it all ... tweeting of the item, "My goodness."
As for why the card is so coveted ... it's an ULTRA rare 2017 Panini National Treasures piece that features Mahomes' signature and a cutout of an NFL shield patch from one of his Chiefs jerseys.