Martin Allen insists that the Spireites will not be fearful of taking on the National League leaders when they head to the capital this weekend.
Martin said: "Everyone is aware how important this next game is to us, as the underdogs going down to London to play Leyton Orient.
"They've got some really dangerous players so it's going to be a tough one, but I don't think we have any fear going to play the best team in the league at the moment.
"We've been diffucult to beat - home and away. Sometimes at home it's been a little bit difficult to be creative with quality play, but we're getting better. The whole thing has changed and it's starting to look like a decent team."
Chesterfield go into the game on the back of an impressive victory over high-flying Salford City, which was followed by a 5-1 FA Trophy win against Basford United.
Martin has praised the attitude and commitment shown by his players. He said: "The players have been fantastic for a good couple of months and I've stuck up for them all the way because they've given it everything.
"None of us can ask any more of those players. They have put full commitment in and they will get their rewards - there's no doubt about that."
Bradley Barry is ruled-out after suffering a head injury in training. "We're well of the FA procedures that have been put in place for head injuries, which we will adhere to strictly," said Martin.
The manager added that on-loan striker Jordan Hallam has picked up a knock which means that he is unlikely to feature.
Spireites Digital subscribers can view the full pre-match press conference here.