The 18-year-old came off the bench during Saturday’s 14-8 win in the first Test at Leigh, given him further confidence in the way that his game has develope under the watchful eye of Rhinos’ coaching staff during the past 12 months.
The former Hunslet Warriors player now hopes England can secure a historic series win in his home city.
“This year has helped me a lot,” said Mustapha. “The training we do at the Rhinos has got me mentally and physically prepared for these two games.
“I have had a short pre-season so far at Leeds, but it has really helped me. I have come a long way . I have to thank my coaches Rob Burrow and Jonny Wainhouse for that.
“They have helped me become a better player plus the nutrition and gym staff at Leeds have helped me become bigger and stronger. If it wasn’t for them, I wouldn’t have got this opportunity with England.”
Mustapha earned a call-up to the England side after impressing for Yorkshire against the Australians two weeks previously.
He was determined to make the most of his opportunity.
“I felt I had a point to prove and needed to show that it was a good decision and I deserved my place in the squad,” he said.
“I was actually shaking on the bench and hungry to get on. Coming off the bench, I knew I needed to raise the level to keep our momentum going.
“It was an amazing feeling and a great experience to get one over the Aussies. I was very emotional before the game and nervous going into the match. It is a big honour to represent my country and to play against Australia.”
Mustapha said confidence was understandably high in the England camp, as it had been before the encounter at Leigh at the weekend.
“We’d had a good week in training and we were looking sharp,” he added. “We knew we could beat them and we worked hard for each other. The win meant so much to everyone.
“It will be amazing to win the Test series at Headingley –we have a chance to write our name in history.”