Kansas City Chiefs quarterback Patrick Mahomes and wife Brittany Mahomes' daughter Sterling is embracing her new role as big sister.

In her Instagram story on Thursday, Brittany Mahomes shared a photo of the 1-year-old holding her baby brother, whose face was not revealed.

"Truly been the best big sissy," the fitness entrepreneur wrote.

PHOTO: Brittany Mahomes shared a photo of her children to her Instagram account.
Brittany Mahomes/Instagram
Brittany Mahomes shared a photo of her children to her Instagram account.

The couple announced the birth of their second child in a joint Instagram post on Monday

In the photo, the baby wore a brown and white onesie atop a blanket with the name "mahomes" printed all over it.

A diamond-encrusted chain that read "Bronze" was also spread across the blanket.

In the caption, the couple shared that their newborn's name is Patrick "Bronze" Lavon Mahomes III.

During a weekly press conference on Wednesday, the Super Bowl winning quarterback shared the meaning behind his son's nickname.

"My brother, Jackson, whenever we were trying to find something that was a little unique and different, said, 'What about bronze? It fits perfectly with Sterling,' so we went with that," Mahomes said, referencing his daughter. "It works out well. He can have his own thing now, where he's not Patrick, he's Bronze, even though he's Patrick. Then he and Sterling can have that connection moving forward."