John Ross' NFL combine record is in serious trouble this week ... 'cause Alabama star receiver Henry Ruggs WILL run a 4.20 40-yard dash in Indy -- so says his Tide teammate.
"Somewhere around that range," Alabama cornerback Trevon Diggs tells TMZ Sports. "That kid's fast!"
Of course, Ross currently holds the mark for quickest 40 time ever at the NFL's marquee pre-draft event ... logging a 4.22 back in 2017.
But Ruggs has a legit shot of breaking that mark when receivers run this week .