Top NFL Draft quarterback prospect Justin Fields was renowned for his mobility as a star for the Ohio State Buckeyes, and he turned more heads during his Pro Day on Tuesday.

Fields ran a stellar 40-yard dash of 4.44 seconds, with one scout clocking the time at 4.43. Immensely impressive stuff from a quarterback, especially when considering that time is faster than a number of skill position players:

Justin Fields might well have made the San Francisco 49ers' decision at No. 3 a whole lot tougher.

Nothing is set in stone with about a month until the 2021 NFL Draft. However, it is all but assured the Jacksonville Jaguars will take Clemson star Trevor Lawrence with the No. 1 overall pick. The New York Jets could select BYU standout Zach Wilson after a tremendous showing at his Pro Day this past weekend. Then the 49ers will be on the clock.

San Francisco got extremely aggressive in moving up to No. 3. All indications are Jimmy Garoppolo is still seen as the starting quarterback, but the Niners are still likely to draft a top signal-caller. There has been some smoke regarding the team's possible affinity for Alabama star Mac Jones. But Justin Fields' athleticism and talent could be tough to pass up.

The Buckeyes star is an explosive runner who can get downhill. That's before even addressing the arm talent, with Fields boasting one of the best deep balls of any quarterback in the class.

Perhaps the Niners still opt for Jones. Trey Lance is also an option. But Justin Fields is pressing hard to showcase his upside as a guy who can get chunk yardage in a variety of fashions.