The uncapped Cardiff Blues number 10 has caught the eye during an impressive debut season of professional rugby, standing out in a poor campaign for his region with his composure and accurate kicking game from hand and tee.
The 20-year-old was set to take part in the IRB Junior World Championship in France but more injury woe for Rhys Priestland, who suffered a recurrence of his Achilles injury just minutes before making his comeback for the Scarlets after six months out, and the decision to rest James Hook, meant Patchell got the call to join the final 27-man squad.
He said: "I am thrilled, I know there is a lot of hard work to go yet, but it is great to have made the cut.
"I was ready to play for the under-20s and had been preparing to go to France with them.
"Unfortunately for Rhys, he picked up an injury and it is devastating for a sportsman when you suffer a recurrence of your injury, but I have got the call and managed to sneak myself in.
"All the uncapped players going out there will want to get some game time, but you can't count your chickens before your eggs have hatched and I will have to work hard to achieve that.
"But the only expectation you have as a player is what you expect of yourself and I have said all year long that my only goal is to improve week in week out, and if you do that you will move in the right direction.
"Time will tell if I am ready to play Test rugby, I cannot say more than that, I may get an opportunity on tour, and hopefully if I get it I can make the most of it."