Rickie Fowler engaged to 'best friend' Allison Stokke

Rickie Fowler's U.S. Open preparations included a big off-the-course commitment.

Fowler announced Friday on Instagram that he proposed to girlfriend Allison Stokke, the former track and field standout at the University of California.

Today is National Best Friend Day so I wanted to lock mine down...I WON!!

A post shared by R I C K I E (@rickiefowler) on

Stokke replied in an Instagram post: "Yes!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! And happy national best friend day to my best best best friend! I love you!!!"

Fowler and Stokke became "social media official" last year. Stokke, 29, was an All-American high jumper with the Golden Bears after a standout high school career in California.

Fowler, also 29, is ranked seventh in the world and has four career PGA Tour wins. He'll head to Shinnecock Hills for the U.S. Open next week looking for his first career major championship.

He came close at the Masters in April. Stokke caddied for him at the annual par-3 contest, then watched as her boyfriend shot a 5 under on Sunday at Augusta National to fall just one stroke behind winner Patrick Reed

"What. A. Week. So proud to stand alongside this man!" Stokke posted on Instagram afterward.