Warren Gatland rues 'disruptive' referee change in 'devastating' World Cup loss

Peyper left the pitch just 15 minutes into the Rugby World Cup quarter-final after he sustained a calf injury.

When the South African official was forced to withdraw and be replaced by Englishman Karl Dickson, Wales were leading Argentina 10-0, but they would let that advantage slip as Los Pumas fought their way back into the match.

Gatland, who insisted he was not criticising Dickson, said that the referee change was significant.

"It probably didn't help the referee getting injured," he said when asked why he felt his side let their lead slip.

"That was a little bit disruptive in terms of the game.

"We were 10-0 up, thinking that we could have taken a couple of the opportunities presented to us, and unfortunately, we gave away a couple of soft penalties that allowed them to go in with a couple of those before half-time.

He added: "It does throw you off [the referee change], we were comfortable with Jaco Peyper and the relationship we have with him in terms of his control of the game.

Follow all the Rugby World Cup fixtures in our live score centre

"It is nothing against Karl, but you do a lot of analysis through what referees tend to be tough on, what they look for.

"We hadn't really prepared for the change. Sometimes that happens in the game, and you've just got to deal with it."

The head coach was also asked about the controversial decision involving Argentina lock Guido Petti and Wales centre Nick Tompkins.

Dickson and his assistants judged that Petti's challenge on Tompkins at a breakdown did not warrant a penalty, despite the Pumas second rower making contact with the centre's head.

"It will be interesting to see what happens in terms of the feedback from the panel," he said.

"If he feels that Nick's dropped his height, he said it wasn't foul play, I would need to go back and have a look at it, I probably think it's at least a penalty situation.

WATCH: Selected matches will also be available on SABC Sport.com's live streaming channel

"From that, we felt Dillon Lewis was on the ball for a significant amount of time before they ended up scoring their try as well. Sometimes those things happen in a game in big moments. That's just the way it is."

Meanwhile, captain Jac Morgan said that discipline cost his side.

"We knew they were going to be a physical team; they always are," he said.

"We just had to front up against that. But discipline and a couple of errors let us down.

"We let them into our half, and they capitalised on that. We let them have more possession, and they got points out of it.

"It is a devastating result."

READ MORE: Rugby World Cup: Argentina book semi-final spot with comeback win over Wales