Robin McBryde says it is "vitally important" that Wales maintain autumn momentum against Tonga on Saturday.

Wales head coach Warren Gatland is expected to make several changes following a first victory since 2008 over Australia three days ago, and ahead of next week's appointment with South Africa.

Wales have not lost since last season's Six Nations Championship, reeling off seven successive wins, which represents their longest unbeaten run of Gatland's 10-year reign.

And it is possible that players such as uncapped Leicester back Jonah Holmes, centre Owen Watkin, scrum-half Tomos Williams, plus forwards Leon Brown, Aaron Wainwright, Ellis Jenkins and Seb Davies will be involved as Wales' World Cup countdown continues.

"Everybody who puts the red shirt on during this autumn campaign leading into the next year realises they have to grab this opportunity with both hands," Wales assistant coach and forwards specialist McBryde said.

"There is the nature of the competitiveness of this squad, and you consider there are a couple of world-class players not available through injury who are going to come back into the mix.

"They know they have to take the opportunity.

"We took a lot of heart from making 10 changes from Italy in the Six Nations (last season) and getting a good victory.

"This autumn is a little bit different because we are two (wins) from two.

"We have got quite a bit of momentum from the Australia game, and it is vitally important we keep that momentum through to South Africa next week.

"We are not looking any further than the next game, and we are going to give Tonga the utmost respect.

"Because we have not lost yet, they (players) have to value the opportunity and build on last week's performance. That is the big message from the coaches."

Wales have sometimes struggled against Tier Two opposition during the autumn, losing to Samoa six years ago, drawing with Fiji in 2010, while edging past Japan 33-30 two years ago and then Georgia 13-6 last season.

Assessing the Tonga challenge, McBryde added: "They are big men. Their set-piece has improved over the years, so they are not just renowned for their line speed.

"It is going to be a different test for us, but a good test.

"They are a very proud nation, and they certainly carry their heart on their sleeves, that's the way they play.

"There are a number of (Wales) players who are chomping at the bit.

"They haven't been given an opportunity yet. So they've got to channel that frustration in training, which they have done, and makes it a very healthy and competitive place for the players to be in."