The Arsenal goalkeeper played for the club for three months in the 2014/15 season, appearing 24 times for the then National League Port - and it helped shape his future.
The teenager walked out at Haig Avenue on loan from Blackburn Rovers, before he switched to London and helped establish Brentford in the top flight.
He says he’ll never forget what he learned in those 13 weeks with his time on Merseyside helping the 19-year-old become a man.
“Those three months at Southport were among the best of my career because they taught me so much - it was like a taste of the real world,” he said in an interview with the Guardian.
“We trained at the local university. You took your kit home to wash and you came with your bag and towel. I was used to that, I’d lived alone since I was 15, but it grounds you, teaches you not to take things for granted.
“There were players for whom the win bonus could be the difference between making it to the end of the month or not, having a bit of money for their kids or paying the water, the gas, electricity, mortgage. If I hadn’t gone, I wouldn’t have see that. Now it’s deeply ingrained in me.”
The Spanish international stopper attributes a lot of his development to Steven Drench, who worked with him for several years in the Blackburn academy as a development goalkeeper coach.
The Chorley goalkeeper and Raya have remained close and the Magpies man said: “"Being from Spain, he had that European way of moving around the goal, but what stood out was his technique, shot-stopping and pure athleticism.”