In a game full of talking points, Wales slipped to their tenth straight test defeat as the Southern Hemisphere nation would overcome ill-discipline to triumph in the Welsh capital for the first time.
In a farcical post-match inquest, Gatland revealed that Wales had incorrectly replaced injured winger Mason Grady in the 17th minute with outside-half Costelow.
Wales had gambled on a 6-2 split on their bench with only two backs available and assistant coach Rob Howley stressed prior to the game that scrum-half Ellis Bevan would replace an injured winger.
The match itself had all looked rosy for Gatland’s side as new cap Blair Murray took a mere eight minutes to notch his first international try. The Scarlets wing finishing off a sweeping move into the corner after good work by Cardiff duo Ben Thomas and Cam Winnett.

A penalty try would be awarded after captain Dewi Lake had been obstructed on the try line to put the home side in the ascendancy at 14-3, but Wales would fail to take the game by the scruff of the neck.
Despite being reduced to 13 men, with both number eight Elia Canakaivata, and wing Semi Radradra sent to the sin bin, Fiji would always be in the contest and exposed a fragile Welsh backline.
Fly-half Caleb Muntz ticking over the scoreboard regularly on his way to a match-winning 19 points in the contest. The Fiji number ten scoring a majestic individual effort skipping past several Welsh defenders to go over the try line in a man-of-the-match performance.
The first half ended with Wales in with their noses in front at 14-10, but Fiji would look the most threatening of the two side’s when back to a full quota.
Two Muntz penalties in the first ten minutes of the second half edged a slender lead before blockbusting centre Josua Tuisova stepped out of two tackles to score a decisive try in the right-hand corner to gain breathing space for the visitors.
Wales would hit back five minutes later to give themselves a chance with a score by replacement Bevan – eventually playing as the makeshift wing a minute after coming off the bench, taking a pass from Winnett to race over the line.

The Fijians though would show composure to see out a late Welsh rally and pounced on a mistake to seal the match. The cool head of Muntz slotting a penalty between the posts to silence the home crowd.
For a diserpointed Gatland, the shoulder of the blame would lie with him, but despite the initial inquest into the record extending defeat, the Kiwi feels his side are going in the right direction.
“I need to get to the bottom of that [the replacement error], said Gatland after the match.
“Ellis was supposed to go on. We were talking and said we’re going to put Ellis on and then Sam’s 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.”
“We are disappointed [with the result] but I still thought there was lots of good stuff about today.
“We talked about what we’re doing in terms of some younger players and they will take a little bit of time.
“It’s our first game in the autumn and you fix a number of those things up and you get a different result the following week.
“We said we wanted to win the first two games, we started really well and we could have been 20 points to three up in that first half and that potentially changes it – you’ve got to take it on the chin.
“At the moment the criticism directed at me is probably a little bit easier, it’s not so much on the players, I’m reasonably comfortable with that.
“I’ve got broad enough shoulders to take that, but we will continue to work hard, keep our head down and we’ve got to come back and prove that for next week.”
[Lead image: Welsh Rugby Union]