Sam Allardyce has braced West Ham for the biggest test of their Barclays Premier League season when Arsenal arrive at Upton Park tomorrow.
The Hammers have made a strong start on their return to the top flight and sit seventh in the league, with three wins and two draws from their first six matches.
Allardyce's men are one place above north London rivals Arsenal - but he knows their honeymoon period is over.
West Ham face all of last season's top six clubs within the next two months, starting with the Gunners, in a period that could define their campaign.
"We have 11 points from six games so we are delighted that our start has been as fruitful as it has been," Allardyce said.
"They (Arsenal) are a top four side. This is a big test for the players and whether they can master the quality of opposition.
"Can they understand what they need to do or change their game slightly to get best chance of a result?
"Arsenal are so good at keeping the ball. We will need to concentrate that they don't get behind us. That is a key area.
"We need to accept that we won't see the ball as much as other home games, Villa, Fulham and particularly Sunderland."
Allardyce will decide today whether or not to start with England striker Andy Carroll, who has returned from a hamstring injury but remains short of match fitness.
Carroll dominated the Arsenal defence two years ago, when he was at the peak of his form for Newcastle before his ill-fated move to Liverpool.
"We will have our game plan and hopefully that will get us a result but that means every player playing at their best," Allardyce said.
"Even then, it may not be good enough to beat the Arsenal. If we reach the performance against Sunderland and Fulham we will give them a really good game."
Chelsea exploited a lack of "authority" at the back, as Arsene Wenger put it, last week but Arsenal could have the more dominant Per Mertesacker back from illness.
Allardyce believes Arsenal's defence has been strengthened since the recruitment of former Gunners centre back Steve Bould to the coaching staff.
"It certainly looks a lot harder or more difficult to break down," Allardyce said.
"What we need to think about is how many opportunities will we get to break it down.
"People have said over the years that Arsenal have been weak at the back but the problem you face is getting to their defence, they're so good at keeping the ball that chances are few and far between."