The futures of Pogba and Grealish have been two of the most talked-about topics ahead of the summer transfer window, with Pogba regularly linked to the likes of Real Madrid and Juventus while Grealish has been strongly tipped to join United, particularly if Aston Villa are relegated.
Pogba has been limited to just eight appearances this season due to injury, whereas Grealish has scored nine goals and assisted eight in 31 outings, and Gray believes that replacing the Frenchman with the Villa skipper would be shrewd business by United.
"We don't know how football is going to come through this crisis. We don't know if football is going to be the same again and if it will affect players' values," Gray is quoted as saying by the Evening Standard.
"But, when the dust settles, if I could sell Pogba for £100m and bring in Grealish for £70m, I'd do it in a heartbeat. It's a no-brainer. United still might be able to get their money back on Pogba. We know his value commercially and on social media with his millions of followers. That's important to football clubs these days.
"But he's pretty much failed at United. Is it his own fault or just bad luck with injuries? I think it's probably a combination of the two. Real Madrid seems the right fit for him - and his agent has been edging towards that."