WARREN Gatland is bracing himself to deliver bad news this week after his Wales players added to his selection headache by smashing Tonga 74-24.

A half-century of unanswered points in the second half at Principality Stadium earned an eight straight Test win, their longest streak since 2004/5.

Victory against South Africa on Saturday would complete a first autumn clean sweep and Wales' first team are being kept on their toes by the 'second string'.

Gatland made 14 changes to his XV from the 9-6 win against the Wallabies but still ran in 10 tries.

The head coach acknowledges that he faces some tough calls next summer when he must whittle his squad down to 31 for the World Cup.

"It's nice to have those headaches. The hardest thing for me about selection is the players who miss out," said Gatland.

"I know how disappointed they are and I expect that because they should back themselves to be in the team. There are definitely going to be some disappointed players (against South Africa).

"This is the most competitive squad we've had. We've always spoken about creating depth and we've done that.

"The pleasing thing for me now is I can pick a bench knowing they are going to have a strong impact as well.

"Then there are guys who are missing out on the match day 23 and are really disappointed because they think they're good enough to be involved.

"That's the most positive thing for me and I think going forwards, Welsh rugby is in a good place.

"We've spoken about the next eight to 10 months and for all of us as a coaching set-up, we've said that when we leave, we want to leave the squad in the best possible position.

"That means being successful up to and at the World Cup."

After a perfect summer of successes against South Africa and Argentina (twice), Wales have stayed in the winning groove by beating Scotland, Australia and Tonga.

"It's been a good autumn for us. Next week is going to be very important for us and if we can win that, then we've gone a couple of campaigns unbeaten," said Gatland.

"It's all about next year, but the pleasing thing for me is we are creating momentum, self-belief and confidence. We're definitely doing that.

"Winning is a habit and so is losing. To continue to win sometimes you have to win ugly and have a bit of luck as well.

"The squad is in a really good place mentally, there is some real competition, and we're building nicely to next year."

The strong performances of his fly-halves - Gareth Anscombe, Dan Biggar and Rhys Patchell - will naturally lead to a debate about who should wear 10 against the Boks, much to the disappointment of the boss.

"All three of the 10s have played well and that’s a great position for me to be in. The biggest thing for me – and the players are the same – is that the last thing we want is a media debate about the Welsh No 10s," he said.

"That’s been going on forever and they don’t want to be stuck in the middle of that. I think whoever is involved against South Africa will see it as a big opportunity and whoever misses out will be very disappointed.

"It’s a position where we have different players with different strengths, but we’re in a good position there."