Joe Hart says missing the World Cup is "hard to take" as the gutted goalkeeper felt he had something to offer England this summer.
Despite playing a key role in helping the Three Lions reach Russia, the 31-year-old's lack of game time and form for West Ham saw him overlooked for the 23-man squad.
Gareth Southgate plumped for uncapped Burnley goalkeeper Nick Pope alongside Jordan Pickford and Jack Butland, with the England manager's respect for Hart meaning he instead asked Tom Heaton to be on the standby list.
Only Peter Shilton has played in goal more for England than Hart and the 75-cap goalkeeper, veteran of the 2010 and 2014 World Cups, broke his silence on Friday morning.
"Not going to lie, I'm gutted," Hart wrote on Instagram alongside an image of the England crest.
"After 2 years of trying to make the most of a really tough situation, this is hard to take.
"I'm proud to have put in the graft and play every minute to qualify with the team and have a really important input in that outcome.
"I know what I bring to the team, but it is what it is.
"Good luck to the team out there, the players know that even though I won't be there, I will have my England shirt on as a fan this time and supporting all the way.
"No fear, go and smash it. (Three lion emojis) and proud x".
Southgate said overlooking Hart and left-back Ryan Bertrand, another regular in qualification, were his toughest selection decisions.
Hart played nine of England's 10 qualifiers, captaining the side at home to Lithuania and producing a man-of-the-match display in Slovenia to sneak a 0-0 draw in Southgate's first match on the road.
Southgate insisted under-fire Hart was still the country's best goalkeeper just last August, but a patchy season on loan at West Ham compounded a topsy-turvy period with Torino the previous campaign.
Hart clearly has no future under Manchester City boss Pep Guardiola and Southgate hopes he resolves his club situation over the coming months and returns rejuvenated.
"In Joe's case, he's been England number one with 75 caps," Southgate said on Thursday. "I don't think it would be respectful to say to him, 'would you go on standby?'
"We either put him in the squad or we think of what he's done up to this point and hope that he resolves his club situation this summer and that he's back contending for the number one shirt, not the number three.
"That I think was the right thing to do."
Asked about his first-choice goalkeeper in Russia, Southgate added: "Well, that will all become evident as we go through the matches.
"I am not concerned by the experience. In an ideal world, we'd have Shilton and (Ray) Clemence who had 50 caps each heading into a tournament, but we haven't got that.
"But we've picked the three best English goalkeepers in the league this year.
"Ben Foster is probably in that group, but he's retired from international football."