Cardiff City's Noah Anyadike broke a record previously held by Harvey Elliott as the youngest-ever player in the EFL Cup.
Anyadike was 15 years and 98 days old when he played on Tuesday night, edging Elliott who was 15 years and 174 days when he represented Fulham in 2018.
The schoolboy, who hobbled off with a muscle cramp in the second half of Cardiff's 2-1 loss against Norwich City.
"It was an incredible evening for him and really well deserved. We've been lucky because he's still in school, so he spent so much time with us in the school holidays," Cardiff boss Brian Barry-Murphy told BBC.
"He's making exceptional strides, and he's a very talented player. We were very clear that he was the best option for this game based on how well he's done.
"I think [we] just [have] to expose him to the level of challenge that he's capable of playing and pushing really.
"As you saw, he's very big for his age. He can play at a very high level, so we just have to keep pushing him to make sure that he keeps getting the exposures and the level of challenge he needs.
"And keep educating him on the parts of his game that he needs to improve because he's so young.
"There are always ups and downs for all players at that age when they make their debut.
"Our job now is to make sure that we protect him, educate him, but also push him to make sure that he can have the education and experience that he needs to become a very important player for Cardiff."
Norwich boss Philippe Clement paid tribute to returning forward Ante Crnac after he capped his 10-month battle to overcome a knee ligament injury with a vital second goal in his side's win at Cardiff City Stadium.
Mathias Kvistgaarden had headed the Canaries into the lead in the 25th minute before Crnac came off the bench on the hour mark and tucked away Jack Stacey's pass across the box with 12 minutes remaining to prove his knee problems are now behind him.
Cardiff eventually got on the scoresheet in the third added minute when Yousef Salech fired in, but it was too little, too late.
"I told him [Crnac] after the game that I was really happy for him to score after 10 months of hard work. All the team applauded him and that showed how they had all lived with him through his injury," Clement said.
"It was super important for him to score the decisive goal and that will boost his confidence. He has stayed mentally strong."
Clement had told his side he hadn't seen their identity in last weekend's 3-0 defeat at Millwall, but he was delighted with their battling spirit in the Welsh capital.
"We had five big chances and we could have scored three or four goals. It was a good team effort, positive given several players who are new in the building showed their quality," Clement added.
"The important thing was the organisation and the mentality of the team. We are ambitious to go as far as possible in this competition."
For Cardiff it was their first defeat of the season and head coach Brian Barry-Murphy admitted to being "disappointed" with the final result having taken his side to the quarter-finals last season.
"We are disappointed to exit the competition because we wanted to progress. We had some good chances but the goal came too late for us," said Barry-Murphy.
Press Association contributed to this report.