Brian Austin Green Says Son Zane, 7 Weeks, Is 'Getting So Big So Fast' in Adorable New Photo

Brian Austin Green/Instagram

Brian Austin Green is soaking up every minute with his youngest.

The Beverly Hills, 90210 alum, 49, shared a sweet new photo with son Zane Walker, 7 weeks, on Sunday, musing over how fast his baby boy is growing. In the snap, the infant is in a carrier on his dad's chest on a walk, yawning wildly as the actor smiles down at him.

"Getting so big so fast !!" the proud dad writes. "Almost 2 months already 🥹"

Commenters debated whether the little guy looks more like his mom Sharna Burgess or his dad, with opinions evenly split.

The 7-week-old is the first baby for Burgess and the fifth boy for Green, who is also dad to Journey River, 6, Bodhi Ransom, 8 and Noah Shannon, 9, with ex Megan Fox as well as 20-year-old Kassius with Vanessa Marcil.

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RELATED: Sharna Burgess Says Brian Austin Green's Sons Are 'Obsessed' with Baby Brother Zane

In an episode of Daily Pop early last month, Green said that the professional dancer was initially "worried" about becoming a parent but has "snapped right into" motherhood.

"She's been an amazing stepmom to the three younger ones that I have, but she was worried," he said. "She was like, 'I don't know if when I have my own baby, if I'll be able to do all the things that you're supposed to do.'"

"Zane's amazing, Sharna's amazing," he said of his growing family. "It's been an amazing experience, it really has."

Sharna Burgess/Instagram Sharna Burgess

After welcoming Zane, Burgess shared a photo of her and her baby boy lying on her chest from a "food coma" in their first official photo together.

"I don't yet have words that can do this justice. I know I look at him and well up with tears at how cracked wide open my heart is and how deeply and unconditionally I love him. I know I'll never be the same again, ever," she captioned the adorable moment in part.

She continued, "I realize I never knew love of this kind or capacity existed and it's beautifully overwhelming to process. I now wholeheartedly understand everything my mum has ever said to me about a mother's love being unlike any other."

"You know, that whole 'you'll understand when you have kids' thing parents say when they are fussing over you. I get it now. I will love him and worry about him until my last breath and beyond. Heaven is a place on Earth, and I found it."