Minjee Lee should be celebrated as the "freaking good player" she is if the 26-year-old becomes Australian golf's first female world No.1 on Sunday.

So says the Perth superstar's younger brother Min Woo Lee as his sister eyes a second major championship of the year and, potentially, the sport's top ranking after this weekend's Women's British Open in Scotland.

A winner of the US Women's Open in June, Lee, currently world No.2, is in position to take Jin Young Ko's top spot with victory at Muirfield.

Women's rankings weren't introduced until 2006, denying seven-times major winner Karrie Webb the accolade.

But if Lee reaches the summit, Min Woo will be the first to congratulate her, saying he has no problem playing second fiddle in the family to his older sister.

"People ask what's it like living in the shadow but it's amazing to see someone that you've grown up with do so good," Min Woo said ahead of the Thursday's first round of the Women's Open.

"She's pretty freaking good. I'm a very proud brother. She does work really hard and that's one thing I've known from a very young age.

"I still learn from it. It's very motivating."

Min Woo, who tied for 21st at last month's men's Open at St Andrews, suspects Minjee "flies under the radar" compared to higher-profile Australian women's sports stars like retired tennis ace Ash Barty and Matildas captain Sam Kerr because "she does her own thing".

"I personally can learn from that," he said.

"Where I like to obviously enjoy and interact with my friends and family and fans, she's more straightforward and does her own thing.

"That's why she's so good. She has this goal in mind and that is the goal - No.1 in the world."

After finishing tied for second at the Women's PGA Championship a fortnight after winning the US Women's Open, Lee warmed up for the year's final major with a joint-43rd in defence of her Evian Championship in France, then a tie for 18th at last week's Scottish Open.

Min Woo said it was tough to adjust to playing in different times zones in Europe after spending most of the year on the LPGA Tour in the US.

"Hopefully this third week she's locked in and ready to go," he said.

"It's not easy to play every week, as we're used to with my sister.

"And sometimes you can throw in a bad tournament. But we all know she's very good so hopefully this is her week."

Lee will play the first two rounds with Ko and the third-ranked Nelly Korda, hitting off early afternoon (9.39pm AEST) on Thursday.

Fellow Australians Hannah Green, Su Oh, Steph Kyriacou and Whitney Hillier all have morning tee times.