Louis Rees-Zammit admits undisciplined Wales survived a major scare and have significant room for improvement after edging an “absolutely brutal” Rugby World Cup classic against Fiji.

The 22-year-old tournament debutant claimed the third of his country’s four tries to help build an 18-point advantage with just 10 minutes to go on a breathless evening in Bordeaux.

But ferocious Fiji roared back and threatened to pull off a stunning Pool C comeback before falling agonisingly short as Semi Radradra’s costly late knock-on saw Wales scrape a thrilling 32-26 success.

Wing Rees-Zammit, who was limping following the full-time whistle, was the exposed man tasked with stopping the rampaging Radradra before gleefully booting the fumbled ball into touch.

“I was stressed,” he told the PA news agency. “They had a massive overlap and I was trying to call players round, but we were getting sucked in.

“When I saw the ball go over, I was like: ‘I’m going to have to try and go low on him here and hopefully get him out’.

“Unfortunately for him he knocked it on and we won the game.

“It was absolutely brutal. It lasted 82 minutes and we had to dig deep and in the majority of our game our discipline let us down, but I think ultimately to get a win is the most important thing.

“You could see it was a brutal game and I’m a bit sore, but a decent recovery now and hopefully I will be ready for next week.”

Wales conceded 17 penalties across the course of a gripping curtain-raiser against opposition who recently upset England at Twickenham.

Rees-Zammit, who was floored by a thunderous tackle from Vinaya Habosi minutes before his score, will look to shrug off his knock in time for next weekend’s match against Portugal in Nice ahead of meetings with Australia and Georgia.

“I don’t think we played at our best at all,” continued the Gloucester player.

“We’ve got a lot to improve and that’s the best thing because we can get a lot better.

“To beat Fiji at not a hundred per cent is great. We know they are a devastating team.”

The Prince of Wales was among a capacity crowd treated to undoubtedly the most entertaining match of the competition so far.

Josh Adams, George North and Elliot Dee were also on the scoresheet for Warren Gatland’s men, while fly-half Dan Biggar added two penalties and three conversions in an engrossing bonus-point victory.

North, who was on the receiving end of an outburst from team-mate Biggar for not kicking the ball into touch just before the break, echoed the relief expressed by Rees-Zammit at the end of a “must-win” encounter.

“That was a proper Test match,” said the centre. “We’re chuffed to get the result, we needed that to start us off well in this World Cup.

“But we’ve got to look at ourselves very quickly. We know what the issues are: discipline and playing in the right areas.

“It was a must-win for us, we needed that to get us on the right path. It was huge for us and we’ve got to tidy up and turnaround to the next one.

“The way Fiji have developed, they were probably the favourites. They’ve got the physicality and flair that they’re known for but they’re also a well-drilled side.

“They’ve got the set piece now to fight and compete with the best of them and their form coming into the World Cup really showed.”

Speaking of Radradra’s late error, the 31-year-old Ospreys man added: “That’s Test-match rugby, you play on the edge of sword, it’s the one per cent (difference).

“You’ve got to take your opportunities and luckily enough they didn’t take that one.”