Out of Anthony Joshua, Deontay Wilder and Tyson Fury ... who does all-time heavyweight great Lennox Lewis think would've given him the absolute TOUGHEST fight?
Answer ... the 6'9" herky-jerky boxer-puncher that rose from the dead to get a draw with Wilder last year ... Tyson Fury.
We talked to the 3x heavyweight champ who ruled the division for a decade -- who's calling the Errol Spence-Mikey Garcia mega fight on Saturday -- and he told us why he thinks his fellow countryman would cause him the biggest problems.