United interim manager Ole Gunnar Solskjaer said Sanchez, who has featured little in recent weeks and missed the last two games with injury, would play against the club he left a year ago.
Sanchez scored 80 goals for Arsenal in 166 appearances in all competitions, after joining the club in 2014 from Barcelona. He then moved to United in January 2018 in a transfer swap with Armenian midfielder Henrikh Mkhitaryan.
Sanchez featured in United's 2-1 Premier League win over Arsenal last April but Friday's match will be the first time he plays in front of an almost 60,000-strong crowd that used to idolise him.
"He'll be involved. I think he'll love it if the crowd turn against him. As a player, pride kicks in and you think 'I'll show all of you'," Solskjaer told United's MUTV channel.
"He's been fantastic in training, his attitude has been spot on so hopefully he'll enjoy the game."
However, midfielder Marouane Fellaini and defenders Chris Smalling and Marcos Rojo all remain sidelined with injury.
"Smalling has started training so hopefully he'll be available maybe next week so it's looking good for him. Fellaini and Rojo are still a bit away," added the Norwegian.
In line with many other clubs, United are expected to rotate their side for the Cup match at the Emirates.
"We have a very good and talented squad. There are players there that need to play and have the quality to play. There will be one or two changes definitely," added the manager, who took over from the sacked Jose Mourinho in December.
United enjoyed some epic battles with Arsenal during Solskjaer's time as a player, including in the FA Cup, and he said they were memorable encounters.
"That's the one fierce rivalry on a football basis of my years between the two of us. Always the closest rivals, they win the double, we win the treble, and the games were just fantastic," he said.
"There were some tackles flying in between the two teams. Fantastic games."
(Reporting by Simon Evans; Editing by Christian Radnedge)
