O'Shea said: "It's been amazing. Obviously the year we've had with the 21s and then at club level as well, it's been amazing. I've played a lot of games, I've learned a lot as well and it's been really positive all in all."

The 21-year-old central defender, who was part of the senior squad last month, has been handed his chance after John Egan and Derrick Williams were ruled out by Covid-19 restrictions on the eve of Sunday's 0-0 draw with Wales, in which replacement Kevin Long suffered a nasty eye injury.

His elevation follows something of a baptism of fire in the Premier League with the promoted Baggies, who opened their campaign with fixtures against Leicester and Everton before a remarkable 3-3 draw with Chelsea secured a first point.

O'Shea said: "I will still be learning to the day I retire, but it's been a massive step up. The players are a lot sharper and better, but I'm learning. I'm grateful to be playing games, the best way to learn is to play games, especially at the highest level, and it will only improve me in the long run.

"I'm really grateful to be playing and I am cherishing the opportunities.

"The first game, it was an awakening as to what the Premier League is like, playing against a team like Leicester.

"We had a tough start with Leicester, Everton and Chelsea with our first three games so I've had to learn quickly.

"You have to adapt to it. I don't think it's something you can be ready for as such, as the difference between the Premier League and the Championship is such a big gap from what I thought."

Adapting to the rigours of international football will be equally difficult, although the experience of club boss Slaven Bilic, who represented Croatia with such distinction during his own playing days, could prove invaluable in that respect.

O'Shea said: "His reputation speaks for itself, the teams he's managed, the teams he's played for too, and he's been amazing with me.

"Obviously it's nice having a fellow defender coach me and mentor me and add little bits to my game that I wouldn't have had before.

"It's just great having someone with that much knowledge there helping me along and obviously giving me opportunities as well.

"He's not afraid to play young players in defensive positions, which is unbelievable for young players because you want to be playing at a young age and, if you're given the opportunity, you want to go out and showcase what you have and improve that way."