Thornton has had to bide his time before stepping up to the highest level, but will do so when he starts for Robin McBryde’s men against Samoa on Friday.
The young Ospreys second row, 22, who captained Wales at Under-20 level, has revealed the pride he felt when given the nod to run out in Apia.
“It’s been building as I’ve been in a few camps now but to finally get my name called out on that team sheet was an awesome feeling,” Thornton said.
“I’ve been champing at the bit to get involved. I’ve been training and working hard and like every young Welsh boy I want to play for Wales. When it actually comes round you get that sensation of pride.”
After losing four players to the British & Irish Lions and seeing Alex Cuthbert ruled out with injury, Wales will field their most inexperienced side in recent memory against the Pacific Islanders.
Tighthead prop Dillon Lewis and hooker Ryan Elias made their first starts as two of seven changes from last Friday’s 24-6 victory over Tonga at Eden Park.
Thornton is partnered at lock by Seb Davies, just 21, while loosehead Nicky Smith joins Elias and Lewis in the front row. Aaron Shingler, Ellis Jenkins and Josh Navidi make up the back-row trio, Jenkins replacing Wasps flanker Thomas Young.
Gareth Davies’ Lions call-up means his Scarlets team-mate Aled Davies starts at scrum-half. Cory Allen replaces Cuthbert on the right wing, while centre Scott Williams drops to the bench.
Tyler Morgan replaces Williams and joins captain Jamie Roberts in midfield.
Thornton is looking to build on the form which has made him a regular with the Ospreys.
“I’ve been playing a lot for the Ospreys this year and being involved in the PRO12 and the Challenge Cup has given me quite a bit of experience,” he said.
“But Test rugby is a completely different animal altogether so I’m really looking forward to the challenge on Friday against a strong Samoan team.”
Samoa were thrashed 78-0 by the All Blacks last Friday, but still boast plenty of talent and their giant pack will be a severe challenge for Wales’ young guns.
Thornton is up for the challenge. He said: “Samoa have a big experienced pack and we have a couple of young guys here looking to blood themselves on the international stage.
“I think it’ll be a good challenge overall. We’ve had a couple of training sessions and we’ve been prepping ourselves well. We’re looking forward to getting out there now.”