The pair are currently enjoying outstanding seasons for their respective clubs in the Premier League.
Foden,20, has scored five goals and provided seven assists in 17 top flight games this season, and put in a man-of-the-match performance against champions Liverpool at Anfield last weekend while Grealish has found the back of the net six times and laid on 10 assists for his teammates in the current campaign.
Grealish and Foden have just eight England caps between them but Rooney already believes they merit a place in Gareth Southgate’s plans for EURO 2020.
"They have to be in the squad and arguably have to play because they are that good," the Derby County boss said about Foden and Grealish.
"Phil Foden has been one of the best players in the league this season, I think Guardiola has managed him really well.
"For Phil, it's about keeping doing what he's doing. He's one of the best players in the league this season.
"Foden is performing excellently — scoring, assisting — and hopefully he can carry that form on with England. He is entertaining to watch.
"When my lad [Kai] used to go into City, I used to see Phil there.
"I spoke to him a couple of times and I could see he's a very level-headed lad. He was there a lot of the time, but it was just general chat, not me giving him advice.
"There are a few players — not just him. I think Jack Grealish brings something different for the national team."