David Moyes is banking on Declan Rice to plug the leaks in West Ham's defence and lead their push for Europe.
The Hammers have conceded 11 goals in their last five matches with back-to-back defeats by Newcastle and Chelsea denting their bid to reach the Champions League.
Midfielder Rice has missed the last four games after suffering a knee injury on England duty last month, but he is pushing to be fit to face Burnley on Monday Night Football.
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And when pressed on why West Ham's previously excellent defensive record has been blemished of late, Moyes had a simple answer.
"Mostly it is not having Declan Rice," said the Hammers boss.
"Is he that important? I think so, yeah. He played in the game where we drew 3-3 against Arsenal so you could take that away, but he is incredibly important.
"We've had him back training a little bit. We're not sure exactly what level he's at but we've got a few days before the game on Monday.
"He's made good progress, we're happy and I would say he's ahead of schedule. So we'll try to keep pushing him on if we can."
The Chelsea defeat last weekend saw West Ham drop out of the top four but they remain firmly in the hunt for European football in some form.
Their surprise success this season has been played out in front of no supporters but fans are set to be in attendance for the final match at home to Southampton on May 23 in line with the Government's roadmap out of lockdown - and Moyes wants something riding on it.
"The last game of my first season was Everton at home, we won and we finished the season well in front of the supporters," he added.
"Last season we drew with Aston Villa, when we had stayed up and were in a good place.
"If we could get the supporters back with European football a possibility, it would be great for the supporters to be back in.
"I really want them all to be feeling 'let's get your injection, let's get your passport out, because we've got Europe for you next year'.
"I can't do that yet because I don't know I'm there. But nothing would give me bigger pleasure than to tell the West Ham supporters: 'Let's get ready, we're going around Europe'."