An iconic squad number at Old Trafford is currently up for grabs following the departure of Memphis Depay.
Club legends such as Robson, George Best, Eric Cantona, David Beckham and Cristiano Ronaldo have filled that shirt down the years.
Sanchez currently wears seven at Arsenal and is facing serious questions regarding his future at Emirates Stadium after entering the final 18 months of his contract.
Robson believes the Chilean would slip seamlessly into Jose Mourinho’s squad, with his profile tailor-made for a prominent role in a jersey that carries extra significance.
“I know that Sanchez seems to be a bit unsettled at Arsenal,” he told Sport Witness.
“He wears number seven at Arsenal.
“I wouldn’t mind seeing Sanchez come in wearing the number seven for Manchester United.”
Alexis has netted 22 times in 40 appearances for Arsenal this season.
Only Zlatan Ibrahimovic can claim to have bettered that return at United, with Mourinho’s men leaning heavily on their talismanic Swede.
He has also faced speculation regarding a summer switch, with no extension agreed as yet to the initial 12-month deal penned upon his arrival in English football.