For Orient these are the two biggest games in decades. Our opponents Peterborough, on the other hand, appear in the play-offs pretty much every other season. So how are Posh fans feeling about the prospect of taking on the mighty Os? I asked Kelly Green - from the Peterborough blog Standing On The Glebe - for her views...
At the start of the season, would you have considered anything but automatic promotion a failure for Peterborough?
Personally no. Of course automatic promotion would have been great but the majority of fans agreed at the start of the season that anything lower than the play-offs would be a disaster so we're still on target.
You did end up pretty far off of automatic promotion - 20 points. Why do you think that was?
We were too inconsistent. We lost 18 games which is ridiculous for a team aiming for promotion. There was also a spell where it seemed we just forgot how to score which of course isn't going to help win games.
Would Orient have been your preferred choice as semi-final opponents rather than Rotherham or Preston?
Definitely. A: It's the easiest to get to, and who doesn't love a London away day? And B: We're very similar teams. We're the same sort of size club and we play in the same style so you would think that would make you the easiest to beat. Of course that doesn't mean we're underestimating you though.
Were the two league games between our teams the play-off semi-finals, Orient would have won on goal difference. What do Peterborough need to do differently to beat Orient this time around?
Tighten up at the back and make the most of the counter. The game at your place was the grittiest I'd seen us play all season so we just need to replicate that over 180 minutes. Easier said than done!
Is there anything that frightens you about Orient?
We know from when you destroyed us at our place that you're dangerous going forward so obviously your strike force. The thought of Lisbie, Cox, or our old favourite Batt, racing towards our relatively inexperienced defence already brings me out in cold sweats.
And finally, how do you think each leg of the semi-final will pan out?
In my head I have us winning at home and getting a draw at your place. Whatever happens I think there will only be one goal separating us at the end of the ties.