As Japan and Scotland await a decision on whether their key game, scheduled for Sunday, can be played in the wake of Typhoon Hagibis, Joseph reacted to comments from Scotland rugby officials that they would take legal action against World Rugby should the game be abandoned.
"In the past few days, through the media reports that I've read, I feel they've undermined the achievement of the Japanese national team," Joseph said.
It was no accident Japan were sitting atop the pool.
"We have played and won three Tests [Russia 30-10, Ireland 19-12, Samoa 38-19] so far and that has put us in the best position within our pool. I would like to remind everyone that this is not a fluke but is down to a lot of hard work by a number of people," he said.
"Everyone in our squad, players and coach, want to play the match against Scotland.
"We all want to earn the right to be considered one of the elite teams in the world. It is important for us to wake up on Monday and understand we are a worthy top eight team or not good enough," he said.
Joseph, a former All Black and coach of Wellington and the Highlanders in New Zealand rugby, said, "I think the key difference between us and Scotland is that we are driven and supported by the whole country.
"My team is motivated by achieving something that is great, not avoiding an embarrassment."
He has made four changes to his side that beat Samoa and said the game was 'the most significant match' in Japanese rugby history.
"That's because we're in a position now where we're top of the table. We have an opportunity to win the pool and, if we can win on Sunday, go confidently into the quarterfinals, and that's never ever happened before. So, in my mind, without doubt that would be the most significant match that Japan has got itself into.
"We know that we're playing a very good rugby team. They're very experienced, they've got a lot of x-factor. It's a team that Japan has never beaten before, so there's a lot of firsts this weekend.
"It's the first chance that we've had to make the top eight, and it will be the first chance that we have to beat Scotland. So, when you've never done something before, it becomes hugely motivating and exciting for the team," he said.