Serena Williams says that since she found out her sister Venus had the auto-immune disease Sjorden’s Syndrome, she has changed her attitude toward her own play. Serena easily beat Venus in the semifinals of the Family Circle Cup on Saturday.

“It’s so inspiring and hard at the same time,” she told reporters. “I’ve been her biggest fan even more so ever since she found out about her disease. I don’t make excuses. I think ultimately I play better because of that. Like I think about my sister and her not even being able to play at some days at her best level, and I think I have zero excuses. So it motivates me to hopefully not lose, because I have no excuse.”