MILLWALL go into this home tie having not lost since December 17 away at Scunthorpe. The Lions have since beaten two Premier League sides, local rivals Charlton and most recently, Coventry City at the Ricoh Arena.
They now sit just two points off the play-offs and could move above Southend with three points this weekend.
Southend are in the last play-off spot, on 46 points, and are coming off the back of a win against then-leaders Scunthorpe.
Simon Cox has been in good form of late, and their January signings seem to have added some good depth to the squad.
Lucas Ball spoke to Southend fan Amy Green ahead of the clash at The Den this weekend.
What made you support Southend?: I'm actually from Nottingham so it's a bit of a weird one really.
When I was a bit younger, my dad moved down to Southend and we started going to games as something to do while I was visiting. After a few years of going to the odd game, we started to go to home and away games more regularly.
I go to games as often as I can, and my dad now has a season ticket. The passion of the lower leagues was something that I loved, and the fact that it genuinely meant something to the fans and players made it so much better.
What did you think of the performance last weekend to beat Scunthorpe?: Unfortunately I couldn't make it to the game, but have had a full match report from my dad since.
It sounds like we played really well and that it was one of our best performances of the season. We did really well to turn the game around and picking up three points signalled to other teams that we are realistic contenders for the play-offs.
What did you think of Southend's business in the January transfer window?: I was slightly disappointed that we missed out on a number of our first-choice targets, but that's always going to happen when you are competing with Championship clubs to sign players.
It's frustrating that every window we leave our business until the last few days. I go to university in Lincoln so it is interesting to see Theo Robinson sign and I'm looking forward to seeing how he does for us.
I think overall it was a decent window, but I would have liked to see us sign another centre-back as cover. It's one of the strongest squads we've had in quite some time, both in terms of spirits and ability.
Who will Millwall have to watch out for on Saturday? Likewise, who will Southend have to watch out for from Neil Harris' side?: Millwall will have to watch out for Simon Cox, who is in great form of late.
Someone like Jermaine McGlashan could be a danger to the Millwall side, and we saw last weekend that he can have a huge impact with his pace.
I think that we'll have to look out for your winger Jed Wallace. He seems to have settled back into your side well, and will be looking for his first goal since returning from Wolves. Our defence can be a bit slow so Fred Onyedinma coming on as an impact sub could be tough for us to deal with.
Finally, a score prediction?: I would love to see a repeat of our game at The Den last season, and for us to run out 2-0 winners.
But with Lee Gregory and Steve Morison I think you will score at least one on Saturday. I'm going to go for Millwall 1-2 Southend.