Manager Sam Allardyce knows the biggest test of whether West Ham's new boys Diafra Sakho and Enner Valencia can last the distance in the Barclays Premier League is fast approaching.
Senegal forward Sakho netted for the sixth Barclays Premier League match in a row as the Hammers beat champions Manchester City 2-1 at Upton Park on Saturday. Ecuador frontman Valencia also impressed, helping set up Morgan Amalfitano for a first-half opener.
Sakho came off for the closing stages as a precaution against a shoulder problem suffered in a collision with England goalkeeper Joe Hart, and is set for a precautionary scan on Monday.
Allardyce accepts only once the hustle and bustle of the English top flight gathers pace will the club be able to judge whether the duo will need some time out.
"We are on a big high at the moment, it is a fantastic feeling, but we are only nine games in and there is a long way to go yet, we still have the difficult time ahead - it will be the end of November and December when all the games come flooding thick and fast," Allardyce said.
"The new players - will they fatigue or won't they? We are absolutely delighted they have all hit the ground running, but they have never experienced this level of physicality.
"They could easily fall into December finding life extremely difficult, the rest of the squad may have to dip in then and help them out while we give them a rest.
"Hopefully it is not the case, but I have to be wary of that."
Allardyce added: "We don't particularly talk to the player about that because we don't want to put any negativity in his mind.
"They are never going to think they are tired when they are winning, but you have to make big decisions on making sure you do give them a rest.
"Look at Valencia's programme this year, it has been absolutely huge. Playing in Mexico, playing in the World Cup, coming straight here, playing in every game, playing four games on international duty, travelling thousands and thousands of miles and yet still capable of running around like he did."
Midfielder Mark Noble hopes the duo can maintain their form - but insists the rest of the squad will not let them "get sloppy".
He said: "The pair of them and the players we have signed have given the whole club a lift, because they are hungry and want to work for the team.
"It is not just being up there, showing a bit of brilliance and then not running for 20 minutes, they work hard as well.
"Personally, and I hope everyone else does too, I will keep on them, so that they don't get sloppy because they have scored a few goals - I will still be shouting at them in the morning at training.
"I have seen it before at this club where players have been doing really well.
"The crowd love them here, and rightly too, but I will be on them every day to keep them on their toes, the manager will I am sure and we all hope they can keep scoring goals for us over the rest of the season."