The Greece defender has called on his team-mates to do the “dirty work” and ensure they match stuttering City at the Emirates Stadium on Sunday afternoon.
Arsenal have won just one of their last 11 games in all competitions and had to battle from two goals behind to earn a 2-2 Europa League draw at Standard Liege on Thursday night.
The Gunners have gone almost four years without a league victory over City, who won 2-0 at the Emirates Stadium last season in Unai Emery’s first game in charge.
The Spaniard was sacked last month following a poor run of results with Freddie Ljungberg installed as interim head coach as the search for a full-time successor continues.
Arsenal currently sit ninth in the table as their domestic season threatens to fizzle out before Christmas – but Papastathopoulos feels victory on Sunday could kick-start the campaign.
“Of course it is a very difficult game.” the 31-year-old said of the challenge of hosting Pep Guardiola’s side.
“Sometimes, these games are games where you can explode. I think we need one good game in our home to explode and I hope we will have that on Sunday.
“But, first of all, we have to run all together, try to help each other and intensity is the most important thing in football, of course you have to have quality but to show the quality you have to first show intensity, win the duels, be tactically-organised.
“I think now the manager tries to explains what he likes from us and I think he gave a lot of attention to the organisation and we work very hard until now. I hope things in the future are going to be better.”
A 3-1 win at West Ham on Monday night ended a nine-match run without a victory and, having battled back in Liege, Papastathopoulos feels confidence is starting to return to the ranks and can be bolstered once again this weekend.
“I think it’s coming back,” he said.
“It’s a big point this. We lost confidence because we didn’t win for a long time. It’s important also, it’s normal for (young) players.
“They don’t have the experience before to live this, to lose their confidence. As a team we lost confidence. Now we try to find balance.
“Maybe. If we win, create and be more organised the confidence is there. It’s not about quality. The team has quality.
“But to show the quality you have to do the dirty work. If you do the dirty work and you’re organised you can win, you can do a lot of things.
“But first of all you have to work on intensity, pace and organisation.”