General View of Ibrox Stadium
Livingston's Knox reportedly impressed Rangers manager Mark Warburton earlier this year, with the Light Blues one of several clubs to have taken a close look at the 16-year-old midfielder.
Rangers manager Mark Warburton
The report claims the Ibrox side have made several approaches to Livi, including a £75,000 offer that was knocked back in January.
However, Rangers' hopes look to be fading, with new Red Devils boss Jose Mourinho set to run the rule over Knox, as his predecessor Louis van Gaal did previously.
New Manchester United manager Jose Mourinho poses with a club scarf
Knox became Livingston's youngest ever player when he made his debut for the then-Championship side four days after his 16th birthday in December last year.
Reports of Rangers' interest emerged soon after, though the Glasgow giants have since heavily recruited in the teenager's position.
Accrington pair Matt Crooks and Josh Windass became the first midfielders to arrive at Ibrox this summer, followed by Liverpool's Jordan Rossiter, Burnley's Joey Barton and Niko Kranjcar of the New York Cosmos.
Joey Barton applauds the Rangers fans as he is substituted