Of Jermain's eight goals this season, half have arrived in games he has started (two at Macclesfield in the FA Cup, one at Manchester United, and one at home to Aston Villa), while four (Ipswich, Charlton and Chelsea away, Derby at home) have come from substitute appearances.
Joe feels that Jermain is ready to go on another extended run of starts in the first team, in the absence of the suspended Paolo, and says: "Paolo has been playing well, but we have Jermain to come in now and the fans are set up nicely for Wednesday night.
"Paolo is a big loss to us, but Jermain is different class as well. We are lucky to have that strength in depth and he will take it in his stride because he is a great striker, too.
"He will score goals at any level, whoever picks him, because he is just born to do that."
He feels the importance of the occasion will suit Jermain, and adds: "It is the biggest game of the season for us on Wednesday night and we are looking forward to it.
"We have got a lot of respect for Chelsea. They are a good side who gave us a pasting the other week.
"They are a big club, and the favourites - but they have to live up to that.
"We have to keep our heads down and do as well as we can. I don't want to build any hopes up - we are just going to go out there and give it our all.
"It will be a 100% performance, and hopefully as organised as we were on Saturday, which will hopefully mean we get the right result."
Joe is delighted at the way West Ham bounced back from the defeat at Southampton last week, and says: "It was a bad result on Wednesday but the lads really worked hard on Saturday and we looked like a team again, whereas Wednesday was a bit all over the shop.
"That is why Glenn is a good manager and there is no falling apart. He gets us in, talks to us, and we get back to it.
"We are one point off eighth place, which is good, and the lads were up for it at the weekend."