Warren Gatland has demanded answers after a breakdown in communication with his technical team saw Wales make a wrong substitution during their defeat by Fiji.

Wales had taken a selection gamble with only two backs and no replacement centre or winger on their bench, a decision which was exposed when Mason Grady was forced off after just 20 minutes with an ankle injury.

With Grady unable to continue, fly-half Sam Costelow provided cover on the wing but Gatland later admitted that scrum-half Ellis Bevan was the intended replacement.

“I need to get to the bottom of that,” said Gatland, whose side led 14-10 at the break but slipped to a 10th consecutive Test defeat. “We were talking and said we’re going to put Ellis on. And then Sam ran on the field. I think he might have assumed he was the person going on. We had already had those discussions with Ellis that if we do lose a winger, you’re going to need to cover us there.”

When asked if he rued his decision to field a six-two split on the bench, Gatland replied: “Probably. We’re going to get a bit of bad luck and it happened today. It’s difficult. We had a long debate about that and a long discussion about the six-two split. The first time you do that and you get caught in the one position you’re a bit vulnerable.”

Despite overseeing a 10-match losing streak in his second spell in charge of the national team, Gatland identified “good stuff” among some of his younger personnel. A total of 16 players in Wales’s match-day squad against the Pacific Islanders had seven caps or fewer.

“We’ve seen development from those youngsters. We’ve said we need some patience and time,” he said. “I understand Test-match rugby is about performing and winning. You control the narrative and write what you want. I’ll see what happens there.”