Michael Keane says his call-up to the England squad "came out of the blue" but has vowed to repay the faith shown in him by interim manager Gareth Southgate.
The Burnley defender was drafted in on Tuesday as a replacement for injured full-back Glen Johnson, marking his first involvement with the senior squad.
And Keane hopes his time working with Southgate in the Under-21 set-up will stand him in good stead as he looks to fulfil his international aspirations.
"It came out of the blue and I didn't expect it," he told FATV.
"I was in the pool at the gym by my house and went into the changing room to a few missed calls from the gaffer [Burnley boss Sean Dyche]. I was thinking 'what have I done wrong here?', so I had to call him back.
"He told me the good news and he was really happy for me, but I was a bit shocked.
"Then I spoke to Gareth and he said that I was very close to being in it anyway, and that I fully deserve to be here.
"He knows what I'm like because I worked with him for a couple of years in the Under-21s, so it's been quite straightforward. He was just really happy for me, so it was a nice conversation. It's one of the best moments of my career.
"Gareth has helped me a lot through my career and given me a lot of chances, so I'm grateful to him. I'm here to prove that I'm good enough, and that's what I want to show him.
"When I came into the Premier League this year, it was always my aim to get into the squad. Now I'm in the squad, I've got my chance so I need to prove that I'm good enough and try to get a cap.
"I think you've got to keep setting goals, and that's the next one."
England face Malta on Saturday before visiting Slovenia on Tuesday.