Big Brother is back with its thirteenth season that started airing on CBS from July 7.

As usual, host Julie Chen ushered viewers in to a whole new season of excitement.

Before we take a look in to the Head of Household (HoH) nominations, let's see the new surprise twists in rules being followed in the latest season, in which three past pairs returned to join the eight newbies in the house.

In this season, all HouseGuests (HGs) were partnered up with another player but everyone will be playing the game as a pair either by their own choosing, or by knowing them from a prior season.

If a HouseGuest wins HoH, their partner will enjoy total immunity from nomination and eviction for the week. The HoH winner will nominate one pair to face eviction, and those two individuals will campaign against each other for votes.

In another twist, the person who doesn't get evicted for the first four weeks will get a Golden Key that automatically exempt the person from challenges, nominations and evictions and makes the person to stay until the Top 10.

Big Brother 13 HG pairings:

* Keith Henderson and Porsche Briggs

* Shelly Moore and Cassi Colvin

* Adam Poch and Dominic Briones

* Lawon Exum and Kailia Brooker

The new 8 HGs swear allegiance to the group against the inbound former HGs.

Following are the former pairs returned to the season Big Brother Dynamic Duos:

* Brendon Villegas and Rachel Reilly

* Jeff Schroder and Jordan Lloyd

* Evel Dick and Daniele Donato

Week 1 Nominations Revealed?

Rachel won the first Head of Household (HoH) after all the HGs hanged onto a giant banana while being sprayed with chocolate and whipped cream.

Keith and Porsche may won the week 1 nominations as these two were paired as part of the twist and both of their house keys are missing from the Memory Wall while everyone else's can be seen on the wall, according to a blog post on Big Brother Network.

Big Brother tradition follows that when someone's key is withheld during the nomination ceremony it stays in hiding for the rest of that week.

The nominations will be officially confirmed on Sunday's Big Brother show, but this seems pretty solid. Of course there's still a Power of Veto waiting to be won, the blog post said.

The Power of Veto competition will be held possibly Saturday or Sunday. On July 13, the first Power of Veto competition will be held, and first live eviction will happen next Thursday.

Big Brother 13 is the thirteenth season of the American reality television series Big Brother. The format of the program remained largely unchanged from previous seasons where a group of contestants, referred to as HouseGuests, are enclosed in the Big Brother House under the surveillance of cameras and microphones. They should have no contact to or from the outside world.

Each week the HouseGuests voted to evict one of their own until two HouseGuests remained on finale night. The winner will be decided by the last seven evicted HouseGuests, collectively known as the Big Brother Jury.

Big Brother will be screened in three weekly highlight programs that will air on Sundays at 8 p.m. (ET/PT), Wednesdays at 8 p.m. (ET/PT), and Thursdays at 9 p.m (live ET/delayed PT) on CBS in the United States and Global Television Network in Canada.

The season 13 is expected to conclude in September, when the winner will be determined and rewarded with $500,000. The runner up is awarded $50,000.