Ole Gunnar Solskjaer missed out on his top strike target in January, with United refusing to accept attempts to include a £66m buyout clause in his contract.
But they remain firm admirers, while Solskjaer is understood to hold no hard feelings against the 19-year-old who he mentored at Molde.
United’s hierarchy are also believed to be understanding about Haaland’s decision to join Borussia Dortmund, despite their attempts to lure him to Old Trafford.
It means they are ready to reignite their interest if Dortmund are open to cashing in on a player they paid £17m for when signing him from Red Bull Salzburg just four months ago.
United have been alerted by Real’s pursuit of the teenager, who has only enhanced his reputation since moving to Germany.
He has scored 12 goals in seven starts for the Bundesliga club – prompting Real to explore the possibility of making him their next Galactico.
United also consider him attainable given his relatively low buyout, with Solskjaer still determined to sign a centre forward this summer.
On loan Odion Ighalo represents a cut-price option at around £15m – but Haaland has long-been considered the No1 strike target.
And with United aware of his agent, Mino Raiola’s, willingness to move clients on quickly, they are preparing to rival Real.
United ultimately dropped their interest in January when Raiola insisted on inserting the buyout clause.
Senior figures believed it would set a dangerous precedent, which would see the super agent have complete control over Haaland’s next move.
Those fears will be justified if the forward is on the market this summer – but that won’t stop them renewing their interest.
Solskjaer is already planning to spend heavily when the transfer window opens, with Jadon Sancho at the top of a wanted list that also includes Jack Grealish and James Maddison.