Chelsea visit the London Stadium for the second time this season in Monday night's Premier League fixture.
The match is already a sell-out and supporters will fill the new ground in the hope of seeing last season's spectacular win emulated or a repeat of this campaign's cup result. In what most fans consider to be their best performance of the season, West Ham knocked Chelsea out of the EFL Cup in a 2-1 win last October.
However, manager Antonio Conte started that game without Eden Hazard, Diego Costa and Pedro and when those three players were introduced in the second half with the Hammers already 2-0 up, the tide of the match changed dramatically. Chelsea's 94th minute consolation came too late to panic the home side in that game, but it is unlikely Conte will be so generous this time round.
Worse, Hazard, Pedro and Marcos Alonso will be itching to get to grips with West Ham's right flank, where Slaven Bilic is likely to turn again to defender Sam Byram to take his natural right-back spot.
As Cheikhou Kouyate had such a torrid time in the club's problem position against Watford in Saturday's 1-1 draw, it's unlikely Bilic will risk the Senegal international in the same spot against Chelsea. In any case, the Hammers will certainly struggle to win anything in the midfield battle unless Kouyate returns to the centre of the park.
If that happens, it will probably be Robert Snodgrass who will miss out against the Blues, the former Hull and Norwich midfielder looking as if he is still settling into life in Stratford. Kouyate may, of course, be dropped if Bilic feels he needs to change his game plan, but the player had one of his best games in the cup win against Chelsea and scored a spectacular header when up against John Terry.
Undoubtedly the best news then is that Andy Carroll is back in training and is expected to lead the line against Chelsea. If the league leaders have a weak spot, it's in the air in the centre of defence and Carroll will be expected to exploit any uncertainty. It's unfortunate for Michail Antonio that he will miss the game through suspension as he is probably vying for the Player of the Season accolade currently; the team will miss his speed and direct running.
Off the pitch though, this will be a good test to see how the new policing is helping security in the stadium. In the cup match, the tensions throughout the game saw seats and plastic bottles thrown and the whole shadow of returning violence helped fuel negativity towards the stadium. Largely due to these incidents however, the club have worked hard with the local police and recent games have seen the hostility evaporate into a more encouraging atmosphere in the ground.
It will be electric against Chelsea -- as long as the Hammers are in the game - and it will be as big a test for the new venue as much as Bilic's frustratingly inconsistent team.