The Leicester duo had started the international break within the Under-21 set-up.
It could be that their next outing sees them win their first caps within the senior ranks.
Gareth Southgate has moved to bolster his numbers after seeing the likes of Luke Shaw pick up knocks during a 2-1 defeat to Spain on Saturday.
He has dipped into the U21 ranks for reinforcements, with Gray and Chilwell making their way to St George’s Park from a training camp in Norwich.
If they are to be involved against Switzerland on Tuesday, then they should feel settled in familiar surroundings.
England are heading to the King Power Stadium in midweek as they seek to get back to winning ways after three successive defeats across World Cup and Nations League competition.
No risks will be taken with his health, with the 23-year-old left-back set to return to Old Trafford on Monday.
Aidy Boothroyd, meanwhile, will be making no additions to his U21 squad.
They are set to take in a 2019 UEFA European U21 Championship qualifier with Latvia on Tuesday.