She won't tell him as much but Minjee Lee has lauded her younger brother Min Woo as a major winner in waiting as the emerging talent hunts down a spot in the Masters.
Lee ended his spectacular European Tour season with a tie for 16th at the DP World Tour Championship in the Middle East on Sunday, enough for the West Australian to finish sixth in the 2021 Race To Dubai.
After clinching a place at next year's 150th Open Championship at St. Andrews, Lee is fast closing on a golden pass to Augusta National as well.
Lee needs to end the calendar year inside the world's top-50 to secure a Masters spot, with the same category in the weeks leading up to the tournament in the first full week of April affording the same invitation.
He currently sits 51st in the rankings following four consecutive top-10 results, which were among eight top-20 finishes from his past 13 European Tour events and a strong showing at next month's Australian PGA Championship at Royal Queensland will do the trick.
Former World No.1 Adam Scott last week hailed the younger Lee a "super talent", but the Perth star's sister has gone further, declaring the 23-year-old capable of landing a major championship.
"I've always thought he was going to be really good but I never tell him because he'll get such a big head," Minjee Lee told AAP.
"He's just naturally talented. If he matures a little more, once he gets a little older, he'll know how to control his emotions a little better and figure out his game a bit more.
"I feel like once he gets to that, there's 100 percent potential that he probably will win a major.
"He's already matured a lot over the past two years that he's played over on the European Tour.
"He's still figuring things out but, to be honest, I feel like he's going to be great, yeah."
It only takes a look at the few who finished above Lee in the Race to Dubai – reigning Open champion Collin Morikawa, former FedExCup winner Billy Horschel, World No.1 Jon Rahm and classy English pair Matt Fitzpatrick and Tyrrell Hatton to see how far Lee has come since starting the year ranked 172nd.
Minjee herself broke through her for elusive first major in July when she captured the Evian Championship in France.
But the 25-year-old World No.7 and one-time No.2 says she's never really felt she owned golfing bragging rights in her family.
"I've always thought he was going to be really good but I never tell him because he'll get such a big head." - Minjee Lee.
"To be honest, I've never really felt like he's been in my shadow, although he must feel like he's been in my shadow," she said.
"But we have such different personalities. I've felt like he was always going to be great.
"He gives a really good show and I feel like a lot of people love to watch him and he's fun to watch.
"So I always thought he was going to be good on TV and out on Tour he'd make lots of friends and be really social.
"And now he's winning too."
Min Woo's Scottish victory came just days before Minjee's Evian Championship win and the siblings were able to celebrate together in America.
"He told me that every single day we had the exact same score and we both won in a play-off," Minjee said.
"What are the odds that could happen? It was kind of creepy but fun and cool in a good way."