The last time these two met at Selhurst Park it finished 3-0 to Palace - but in the return fixture they lost 3-0 so there aren't too many clues for us there. Both have players of tremendous ability in the final third and this could be a case of which side defends better.
In that respect, I can understand why Brighton are seen as the favourites.
Palace lost their first three games this season and Dougie Freedman did an incredible job to turn things around and get them into the top six. However, under Ian Holloway they ended up limping into the play-offs with one win in 10; failing to score in six of those games. They lost their mojo to a degree as defensive frailties came back to haunt them.
They've had an unbelievable season because everybody thought they would drop out of the top six with sides like Bolton and Nottingham Forest seen as bigger clubs. They should be very proud of themselves for getting in there, but Holloway must be concerned about their form.
They must make home advantage count in the first leg. I've never known a set of supporters sing as much as they do and I believe they need a two-goal lead to take to Brighton if they are to reach Wembley.
Maybe the scene is set for 31-goal Glenn Murray to haunt his former club Brighton? With Wilfried Zaha and Yannick Bolasie supplying the bullets they certainly have the individual talents to do so. They will look to get those players on the ball as much as they can and create an inhibiting atmosphere for Brighton in that first leg.
And don't forget Kevin Phillips. I watched his hat-trick against Hull in March and he was absolutely irrepressible; maybe he'll write another script for himself this week?
However, you can see why Brighton are the favourites for promotion. They're strong, solid and they have a fluid midfield system that can hit you from anywhere. With 18 goals in the last nine games it's clear Gus Poyet has built a squad capable of promotion.
Craig Mackail-Smith and Ashley Barnes have got 20 goals between them this season, but the big stars of late have been David López and Andrea Orlandi. They have several matchwinners and I haven't even mentioned Kazenga LuaLua - who scored twice in the final game against Wolves.
Poyet changed the shape of his team as the season went on, dropping Mackail-Smith and finding ways to make his team more potent in the final third. They kept a lot of clean sheets early on, but had too many draws and now he has found a way to win.
Brighton should have plenty of confidence going into a two-legged clash with their arch-rivals because they are the form team. They are better-equipped to win the tie over two legs because they combine solidity with potency.
I think Brighton have got too much in their armoury for Palace, but both sides have been open of late and if each side plays to their potential this could easily be 6-5 over two legs.
But even though I have mentioned all the attacking talent that will be on show from both sides, I think it'll be Brighton's solidity that sees them through. The experience of people like Wayne Bridge could be so important.
But remember, this is the Football League. This division has proved to be a coupon-wrecker on numerous occasions this season and the pressure cooker of the play-offs often rewards the mentally-strong players, rather than the gifted ones. If you can concentrate and focus as if it was any other game then you've got the magic formula.
I'm so excited to be working on the second legs of these ties and if we get anywhere near the drama and intensity of the League One and League Two semi-finals then we should be in for a treat.
Join us for excitement, high drama and goals galore over the next few days.