There's one outfit that could indicate who wins The Bachelor.

With just eight girls left in the Bachie mansion, competition is getting fierce.

But not quite as fierce as the unofficial competitions going down in front of the TV each week as family, friends and colleagues fight to try and pick the winner.

It’s getting tough. But fortunately we think we may have cracked the code, with a convincing theory that could very well predict who wins The Bachelor.

And it’s all to do with what the contestants are wearing at the cocktail parties. The secret weapon to Richie’s heart? The jumpsuit.

@styliststringy my fav look to style from Ep 3 @thebachelorau @thebachelorettesau @alexandranation #styling in #pantsuit #jumpsuit @guess @guessmarciano @marciano @tailormaidpr #choker @kookai_australia @twobirdstalking #earrings @samanthawills #palmcuff @sallyskoufis #heels @windsorsmith #redcarpet #sydneyfashion #sydneystylist #sydneystyle #sydneystylist #sydneydesigner #melbournestyle #melbournefashion #melbournedesigner #fashion #styling

A photo posted by AnneStringer FashionTV Stylist (@styliststringy) on Aug 4, 2016 at 12:42am PDT

It’s dominated this season ever since Olena stunned in her slashed neck navy blue number in the very first episode. Now, we have a pretty good idea why.

It’s a theory that’s been brewing for a while, but it was all but confirmed in the single date in last night’s episode.

“We discovered this week that Richie’s got a little bit of a thing for jumpsuits, you guys. Steph was on the single date this week and one of the first things he said was ‘You look absolutely incredible. Love the jumpsuit’,” Entertainment Writer Jess said on our Bach Chat episode.

“Then Alex was wearing a jumpsuit at the cocktail party.. so what do we make of the jumpsuit conspiracy?”

Listen: We break down the jumpsuit conspiracy in the latest episode of Bach Chat. Post continues after audio…

“Yes, because remember when Olena walked in at that first night and she was wearing a jumpsuit and everyone is like ‘Groundbreaking, no-one ever wears a jumpsuit’, and then he eyed her as he walked away, is is the secret weapon of The Bachelor?” added Entertainment Editor Laura.

Past contestant Eliza, agreed that there’s was definitely something in it.

“I am the biggest fan of the jumpsuit that’s for sure. It’s just so playful and cute and you can do leg spreads without being off-putting,” she said.

Not convinced? Let’s examine the evidence.

The compliment towards Steph’s jumpsuit (okay, so it’s actually a playsuit but we’ll give Richie the benefit of the doubt that the difference can be confusing) is a clear sign he’s a fan, but looking at who else has worn them is even more telling.

Image: Channel 10/Screenshot

If we look at the cocktail parties alone, there are just a select few who have been allowed to wear the jumpsuit, including Alex, Nikki and Olena.

One is the recipient of the white rose, the other was taken away into a secret hiding spot just so Richie could get a sneaky pash in the middle of a cocktail party and the other has him ~entranced~ by her ~mystery~. Post continues after gallery...

Even better, 24 year old mother of one Alex is not only a firm favourite - she's the only one to have worn a jumpsuit more than once.

Steph also wore one last week - and managed to nab the next single date.

Yes, Kiki and now-eliminated Keira and Noni have also worn the all-in-one to the rose ceremony BUT they did all make it through to the next round the weeks they were wearing them. Coincidence? I think not.

"BUT WHAT ABOUT THE PLAYSUITS?", I can hear you saying.

Georgia and Laura. Image: Channel 10

Ignore them. They don't count at cocktail parties. They're a guise designed to distract you from the truth. (Except for the one time Nikki wore one, because she's Nikki.)

So there you have it - the favourites have been marked. Let's just say we'll be watching tonight's episode VERY closely indeed.

Image: Channel 10/Screenshot