Nadine Chalmers-Ross is nursing a secret

Nadine Chalmers-Ross has been wearing a sling for a broken collarbone - but removes it while in front of the camera.

She started her first stint on Breakfast only this morning, but Nadine Chalmers-Ross has already admitted she's been keeping a secret from viewers.

Chalmers-Ross is filling in for Alison Pugh alongside Rawdon Christie on TV One's morning news and chat show after Pugh went on maternity leave.

But there's one thing the 29-year-old hasn't been telling viewers - she's nursing a painful broken collarbone and struggles to dress herself in the morning.

"Sadly, I think that's going to be one of the most challenging things about the new role - just getting dressed in the morning," Chalmers-Ross tells Woman's Weekly.

The 29-year-old tells the mag it's meant she needs to get to work even earlier to allow time to get dressed after tripping on a tree root and breaking her collarbone while training for the Auckland Half Marathon.

Chalmers-Ross has been wearing a sling on her right arm - but she takes it off when she's on air.

It isn't the first time the self-described "complete klutz" has broken a bone. The "porcelain kid" also broke her right wrist while putting out her recycling, her femur, and her left wrist snowboarding.

Chalmers-Ross tells WW she had broken so many bones she checked in for a bone scan to make sure she wasn't suffering something more serious.

Her fiance, Dan Higgins, has banned her from sport before their wedding, she tells WW.

At the time of the break, Chalmers-Ross posted this photo to Instagram.

Chalmers-Ross has been employed as a fill-in presenter on Breakfast, but was confirmed as the show's new co-host on Friday.

The Herald understood it was the third time Chalmers-Ross had applied for the position.

In a statement, Chalmers-Ross said she was used to the 3am starts the job demanded and she hoped to "do her and the team proud".

"I'm really looking forward to stepping in as co-host on Breakfast while Ali is away. It feels very natural as I've been part of the Breakfast family for many years now.

"I love the team and I'm all too familiar with setting my alarm for 3am."

Pugh is expecting her first child with Jo Barus and is returning to her hometown of Christchurch for the birth.

"I'm sad to be leaving but Nadine will do an amazing job. I look forward to watching the show from the comfort of my living room for the next wee while," Pugh said.

- nzherald.co.nz