"Everybody at the academy was delighted with Ashley's appearance because it's a just reward for how hard he has worked," Rioch said to the club website.
"He's been champing at the bit for quite a while now and he is capable physically to play in the first team.
"All the boys that have been involved with the first team this season still have plenty to learn if they want to maintain a permanent spot but that's the ultimate goal.
"Ashley is the kind of player who will get bums off seats because he has pace to burn and we're all delighted with the progress he's made. He just has to take this opportunity now and grab it with both hands.
"It takes a brave manager to put kids into his side and it also shows how well the boys have done. "But Chris Coleman has showed he is prepared to do just that and give them a chance so now it's entirely up to the boys."
City U18's are in action on Saturday when they take on West Ham United at home.