Both Johnstone and Henderson have been capped by England and are eyeing a place in Gareth Southgate’s Euro 2024 squad.
Johnstone has made an strong start to the season and Henderson will know cup matches offer him the best chance of impressing sufficiently enough to dislodge his team-mate and friend.
Only three goalkeepers who have played all six Premier League matches so far have conceded fewer goals than Johnstone. He has been excellent since Roy Hodgson brought him into the team late last season.
Yet Henderson, whose England debut and only cap came in 2020 when he was 23, has never lacked self-assuredness.
“I am a very driven individual, so I think now is the right time for me to go and hopefully maximise my potential”, he said when leaving United for Palace last month.
“Sometimes my confidence comes across in the wrong way, but I just don’t want to look back on my career and think I haven’t reached my full potential.”
Hodgson will make plenty of other changes to his starting line-up tonight. He was pleased with Palace’s four summer signings but feels his 26-man squad lacks depth.
Injuries are also an issue, with Michael Olise and one of those new signings, Matheus Franca, not due back until mid-October.
“We’ve got to use our squad”, said Hodgson. “It’s a little bit disappointing, because at the start of the season I didn’t envisage our current situation. I thought we might give [the cups] a real go. We’ll still give it a real go, but the team that plays might look different.”