My guess is:

Sia
Shawn Mendes
Emeli Sande
Kings of Leon
The Weeknd


That's just looking at the charts, I'd also guess

Sia with Saara Alto
Emeli Sande with 5AM
Shawn Mendes with Matt Terry

I'm thinking the above might be a lot of high profile guests for the show.

I would have preferred Drake, Childish Gambino and some more Craig David?

Think Little Mix are a certain. They just announced their next single on Twitter.

Knowing Simon it'll be Little Mix, Fifth Harmony, Louisa Johnson, James Arthur and all his other Syco/X-Factor connections...

Little Mix - 5am
Robbie - Matt
Nicole - Saara (god help her)

As it is pretty much the most open final ever, I feel the producers can decide their winner with the duet partners and who they choose to assign them to.
I fear if Matt gets someone like Ed Sheeran, he will romp it.
I don't see Sia agreeing to appear at all.

Nicole can't sing with another act this is not going to happen.

Tbh they've probably given so much money in royalties to sia she might agree LOL

I so hope you're right, but give her a mic and stage and she'll do her damnest for self -publicity.....plus Simon has a very soft spot for her.

Nicole sang with Sharon's act in 2013.

Sam Bailey!

don't know don't really care

Her own acts were out of the comp tho!

sia was on last year so no reason why she wouldn't this year

I thought kylie was scheduled to perform.

little mix are certs, we havent seen 5th harmony yet so they will probably appear

robbie might reappear as might emile sande

there's not really many big names releasing at the moment to appear.

I think they should ask Calvin Harris to do a short dj set that would get the atmosphere going

They need to get Sia.

The guest acts this year have mostly been better than the previous few years. They had Adele and Coldplay the previous few years as the main acts. Absolutely no idea who it'll be this year but some people will obviously reappear.

Sia/Saara duet would be incredible.

They should have held Zara Larson back a week so they could have Saara/Zara!!

Kylie Minogue is performing both on her own and with all the contestants in a group performance.

Really? Yay! The guests have been pretty good this year, much much better than last year (bar Adele).

I think it will be a massive Syco fest at the final, James Arthur, Little Mix, Fifth Harmony, Louisa probably all have new singles coming out soon.

Apart from that I'm not really sure, my predictions have been quite correct so far, but I've run out of people to list now! Possibly The Weeknd, Maroon 5, Sia, Calum Scott?

Surprised they didn't mention anything tonight. I'm sure in last years semi final episode they said they'll be joined next week by Coldplay, One Direction, Adele etc.

It would be strange for them to not have it nearly confirmed at this stage. You're right, it is strange. They must be doing some big press in the week instead.

12.05am will appear with Louis and Sarra will appear with Sharon.

They can both sing can't they ???????

Think it's pretty much given that Nicole with duet with Matt. We'll probably see Little Mix duet with 5AM and Fleur duet with Saara.

Since they've not announced anyone in advance I'm not expecting any huge names for the duets this year.

Otherwise, it'll probably be James Arthur, Fleur, Little Mix, Louisa and Fifth Harmony as the guest performers.

Emily was going to duet with James Arthur had she got through to the final. Dan Wootton said that Louis Tomlinson may perform if his debut material is ready. He's the only 1D member to have stayed with Syco. I was thinking maybe that's why Simon doesn't seem as keen on Matt Terry as he was. He already has a new male solo artist to promote. Does he want a Louis Tomlinson lookalike on his books?

Fleur has said in her Evening standard X factor columnist blog that she would love to duet with 5AM with big production and dance break I dunno if that's a secret code or forewarning or her being their guest singer - got a feeling it could well happen! And I reckon Matt will do secret love song with little mix and Saara will get Nicole

No, they didn't announce it last year either. They announced the guests on the Thursday Xtra Factor last year (although they leaked earlier in the day).

They didn't announce any of the guests on the results shows last year though whereas they have this year though so I did think they might say something last night.