Head coach Joe Schmidt appeared frustrated by the state of the pitch at Ireland's captain's run on Friday.
Greg Feek, the scrum coach, revealed World Rugby has given both teams "assurances" the surface remains safe, however.
There were concerns over whether the match in Fukuoka would go ahead, as Typhoon Hagibis closes in on Japan - with England's meeting against France and New Zealand's game versus Italy cancelled - although it will be played as scheduled.
"You guys are pretty smart individuals, and you would have seen the pitch yourselves", said Feek.
"From our point of view, as soon as we knew we had a game on, no matter what happens on Sunday we need to win our game", he said.
'I don't want to predict anything or cause any more controversy at this stage.
"We just try to back the players, trust that the pitch will do its job". So, we're trying to alleviate any concerns while we're out there but then it's just a matter of wait and see.
"The referee will be aware of it, and what's key is the communication is there".
Ireland winger Keith Earls has scored 30 tries in his 80 appearances, including eight in the Rugby World Cup - the most by any Irish player. That's the way it felt out there today.
Ireland will be wary, but given what is on the line for them if they do take five points, Schmidt's team will go in with confidence that they can get the job done.
The pitch will nearly certainly cut up tomorrow, especially at scrum time and Feek admitted that he was anxious about it.
"It's been a challenge selecting this squad, but the great thing about it was that we knew we had a group that really wanted to be here, who sacrificed a lot to be here".
"As Earlsy said, it's fine running around out there, passing, kicking the ball, jumping, tackling and all the rest of that stuff, but when it comes to a static, isometric position like that where there's impacts going on, you're always going to be a little cautious and ask the questions". "Sometimes you've just got to make sure, when you're looking after the ball, that you can retain it and keep the pressure on, keep the squeeze on".
"I just couldn't do that to myself and the jersey and it just didn't cross my mind".
"We saw a few grass patches but it's actually A grade grass, I think it just needs a bit more time, but there's nothing we can do about that now".
"We need to get out and get a result".
"It's about what we can do to give ourselves a chance to get into the quarters and take another opportunity", the No 8 said.
While the combative flanker did not delve into any structural or political issues, Lam's calls for change ultimately fall at the bosses of top leagues and World Rugby.
Tensions have risen ahead of the final Rugby World Cup pool match between Japan and Scotland in Yokohama on Sunday, with Typhoon Hagibis still threatening to scupper the tie. The primary driver was player welfare.
Samoa have lost each of their last 10 games against Tier 1 opposition at the Rugby World Cup, their last such victory coming back in 1999 against Wales. "While the look of the turf may not be ideal, as would be expected with a very recent installation, we confident that the pitch will perform superbly".