Back in 2008, Johnson ran a 4.24 40, which still stands as the fastest electronically timed 40 in combine history. You can see Johnson's blazing fast 40 below.
With the combine kicking off on Wednesday, one of the biggest questions will be: Can anyone break Johnson's record?
NFLDraftScout.com's Dane Brugler wrote this week that he thinks the fastest 40 will come from one of three players.
One of those players is Miami's Phillip Dorsett, who told NFL Network draft guru Mike Mayock that his goal for the combine was to run a "'4.3 or better.'"
Another player who Brugler likes is Auburn wide receiver Sammie Coates. Brugler also notes that you should keep an eye on Florida State cornerback Ronald Darby, who won a 100- and 200-meter state track championship in Maryland while in high school.
Coates and Dorsett will be running their 40 on Saturday, while Darby will be running on Monday.
Of course, if a receiver or corner doesn't break the record, there's always a small chance that a running back will. Of the 10 fastest 40 times since 2005, four have been by a cornerback, four have been by a receiver and two have been by a running back, including Johnson.
So will the record fall? The prediction from CBSSports.com draft expert Rob Rang is no.
Coates, Darby and Dorsett won't hurt their stock too much if they don't break Johnson's record, but their stock will probably take a dive if the don't beat Tom Brady's tortoise-like 5.28 40 from 2000.