Ireland number eight Jack Conan is set to miss out on playing a part in Saturday's crucial World Cup Pool B game against South Africa in Paris.

Conan is recovering from a foot injury.

"Probably Jack's the only one that's slightly behind in terms of being able to get himself right for this weekend," said defence coach Simon Easterby.

The back-row forward sustained the injury in Ireland's opening World Cup warm-up game against Italy on 5 August.

"He's done incredibly well, as have the medics, conditioners to get him up to speed.

"He's actually probably on track from where we thought he'd be, so he's done really well, happy with his progress."

Hooker Dan Sheehan (foot) and prop Finlay Bealham (head injury assessment) are in contention to feature against the Springboks.

"Finlay and Dan both trained really well today [Wednesday], so they're back in the mix," added Easterby.

The Ireland defence coach concedes that the match-up with the Springboks is the occasion that everyone in the Ireland camp has been building up to.

Andy Farrell's men head to Paris for the standout fixture in Pool B seeking to secure a spot in the Rugby World Cup quarter-finals with a fixture to spare.

"I think everyone always knew this game was the big game we had in the first three rounds.

"We built up nicely through Romania and Tonga and have ironed out a few things in our attack and the same defensively.

"We were tested way more against Tonga so I think we always knew this was going to be the pivotal game leading up to Scotland two weeks after.

"People will talk about South Africa and what they will bring but we're confident and trust in what we've been doing, not just recently, but in the last one and half, two years.

"When we play well and in a certain way we are difficult to play against and difficult to beat. This is what we have been building towards so hopefully people will see a bit of that on Saturday."

Easterby added that the Irish must be adaptable and prepared to grind out an "ugly" win against the reigning world champions.

Ireland have won 27 of their last 29 Tests and have often entertained during that remarkable run of results.

The world's top-ranked nation will once again look to deliver their easy-on-the-eye style on Saturday evening at Stade de France.

Yet Easterby accepts that may not be possible for the full 80 minutes against a physical Springboks side sporting an intimidating seven-one split of forwards and backs among their replacements.

"We haven't had to win ugly maybe too many times.

"It would be great if we could throw the ball around and score plenty of tries, but we know that we have to do things in the moment and make sure we're adaptable and that might mean playing certain ways in certain parts of the game," said Easterby.