Nantes (France) (AFP) - Ireland will hope to beat Tonga and come through injury-free on Saturday in their Pool B match giving themselves the perfect boost ahead of their Rugby World Cup meeting with defending champions South Africa.

Tonga wth several former New Zealand stars in their line-up should certainly give world ranked number one side Ireland a tougher examination than Romania did in the 82-8 pasting last Saturday.

Ireland will be seeking to avoid a repeat of the upset defeat by hosts Japan in their 2019 pool game but Tonga have caused surprises in the past beating eventual finalists France in the 2011 pool match.

AFP Sport picks out three potential key things surrounding the match:

Sexton risk factor

Johnny Sexton would ordinarily probably have sat this one out.

However, after dusting off the cobwebs against Romania last Saturday, following a near six month absence, this gives him more game time with the Springboks a week away.

The 38-year-old should if everything runs smoothly become Ireland’s record points scorer, he is just nine points adrift of his predecessor as fly-half Ronan O’Gara.

Nevertheless there is a risk factor too in pitching him in opposite the tough tackling Tongans – losing the man that makes Ireland tick would be a body blow to their hopes of even making the semi-finals for the first time.

Sexton, though, says the hard knocks are part and parcel of the game and you would not survive if you went out worrying about that every time you played.

“When you play rugby, you’ve got to be prepared to be injured,” he said after the Romania game.

“It’s a tough game, it’s physical, and if it happens it happens.

“I can’t go into games worrying about anything.

“I’ve just got to go and play and hope your body holds up.”

The Tongan ‘All Black’ effect

With all due respect to previous Tongan squads this is probably their strongest, bolstered by several former New Zealand stars returning to their roots.

Thanks to eligibility rules this has been possible and the Tongans will hope the impact is a positive one.

There are four in the starting XV – including centre Malakai Fekitoa a member of the 2015 New Zealand World Cup winning squad – which is captained by former New Zealand Under-20 tight-head prop, Ben Tameifuna.

Ireland head coach Andy Farrell believes their inclusion will make it a harder task for his players but perhaps ideal preparation for South Africa.

“There are people coming in for the first time, they’ve been training within that group and all they’re going to do is make those performances that we’ve seen stronger,” said Farrell.

Tonga assistant coach Zane Hilton, though, says their introduction will not dilute the Tongan sense of identity.

“They (the ones who played for other nations) bring excellence but we are ‘Ikale Tahi we do it our way,” said Hilton.

“Those guys are very much about adding new ways of doing things but it is really important to keep that legacy of who we are ‘Ikale Tahi.”

Tongans given free rein

Fiji have worked on a more disciplined structure which came near to paying off against Wales last Sunday.

Tonga, though, will be given a freer rein to mix their eye-catching back play with a trademark ultra physical game.

Tonga’s assistant coach Zane Hilton says it is important to let this flow rather than restrain them.

“I have worked with a lot of teams round the world and mindset is their (the Tongans) greatest quality,” said Hilton.

“The players we have in the group have a mindset of sheer excellence around wanting to drive their performance and improve every day.

“The mindset physicality is part of who the boys are.”

Hilton says it is important to let this flow rather than restrain them.

“For us as coaches it is really important to give them freedom to bring it out and express themselves round how they want to play the game without giving too much structure,” said the Australian.

“It is important for us, the whole world to see the individual skills and talents they have got.”