Wales boss Robert Page explained the shock inclusion of Cardiff midfielder Rubin Colwill in his Euro 2020 squad by saying the 19-year-old "blew us all away" in training.
Colwill has played just 191 minutes of senior football since making his Bluebirds debut in February.
But, after taking his place in Wales' pre-Euros training camp in Portugal this week, Colwill has made the cut for the final 26-man squad skippered by Gareth Bale.
"He's been a breath of fresh air since he's come in," Page said of the uncapped midfielder who began the season playing academy football.
"He just blew us all away with how he was and how he conducted himself. He's a top professional already and a great lad to have around the place.
"He's really impressed me, he's got a presence and maybe something we've not got in the middle of the park.
"He can play off the right, he can play as a 10, he can play in midfield – and that's a bonus as well when you're looking to pick a squad."
There are eight survivors from the group which reached the Euro 2016 semi-finals in France – Bale, Aaron Ramsey, Ben Davies, Chris Gunter, Danny Ward, Joe Allen, Jonny Williams and Wayne Hennessey.
Ramsey and Allen, who were both named in the official Euro 2016 team of the tournament, and Davies are all included despite having had injury concerns over the last few months.
Stoke midfielder Allen would have missed the tournament had it not been postponed for 12 months from last summer because of the coronavirus pandemic.
The 31-year-old suffered a ruptured Achilles in March 2020 and has been declared fit despite missing the last two months of the season with calf and hamstring problems.
Swansea's Ben Cabango, who celebrated his 21st birthday on Sunday, was selected ahead of Luton central defender Tom Lockyer, and Manchester United's Dylan Levitt got the nod in midfield over Newport's Josh Sheeham.
As expected, Euro 2016 hero Hal Robson-Kanu – released by West Brom last week – missed out after being omitted from the Portugal training camp.
Derby forward Tom Lawrence, who missed Euro 2016 through injury, and Schalke winger Rabbi Matondo were also overlooked.
Page told the Football Association of Wales' media channels: "I've had to make some tough decisions and there's some disappointed people around and leaving the camp, which is not easy.
"I said to the 26 lucky ones that we've got such a good group, and they're really tight together, that it's been a hard day.
"If I could have taken 31 I would have because they're such good characters, but we have to make these decisions and move forward."
Wales start their Euro 2020 campaign against Switzerland in Baku on June 12 before playing Turkey in the Azerbaijani capital four days later, and then completing their Group A fixtures against Italy in Rome on June 20.