The American is used to setting the pulses of her social media followers racing with candid sultry snaps and glam pictures from photoshoots.
But she went for a more modest look in a recent Instagram video advising her fans on how to improve their golf game.
Spiranac, 31, donned a matching blue two-piece outfit that greatly accentuated her figure and struggled to keep her fully contained.
Her followers quickly noticed that she was wearing less makeup than usual and that she’d changed her hair colour.
In response to a question about her new look, she wrote commented: “[I] changed my hair colour and [I’m] wearing a lot less makeup than normal.
“[I’m] going for a more natural look.”
Spiranac flaunted her new hair and make-up-free look in a stunning selfie thanking fans for their birthday messages.
In the accompanying caption for the snap, in which she donned a red top that she nearly spilled out of, she wrote: “Thank you for all the birthday wishes xoxo.”
Spiranac – who boasts a whopping four million Instagram followers – is a former professional golfer who competed on the pro circuit for a year.
Recalling her one-year stint on the pro circuit, the bombshell said: “From the start, it was a massive controversy I was there.
“There were pros, legends of the game, discussing if I belonged.
“I completely bombed, publicly cried about it. “It was a s*** show.”
Hitting back at her detractors, she said: “What I produce is not that provocative.
“If my body makes someone uncomfortable, that’s not my problem.
“I’m not doing anything illegal. I’m not causing harm. Maybe it is because I come off as every guy’s fantasy.
“A girl that loves golf and wears a bikini – but I see myself as a girl’s girl. I’m coming from an authentic place.”