LeBron James says he's got next after a mysterious Fortnite session popped up on the Fenway Park scoreboard this week ... calling on his fellow Boston Red Sox owners to let him use the big screen to get in some Madden action of his own!!
A clip from outside the historic stadium made rounds on social media on Thursday ... showing an unidentified enthusiast playing the popular video game on the massive outfield display.
King James -- who owns an undisclosed amount of Fenway Sports Group, which includes the Sox -- got wind of the epic moment .