S. Sivasangari has beaten the younger sister.
Today, the national No 2 will have to beat the older sister to reach her second Ohana National Squash Championships final.
Sivasangari, the second seed, overcame 16-year-old Aira Azman 11-4, 14-12, 11-2 in the quarter-finals of the women's Premier division at the National Squash Centre, Bukit Jalil yesterday.
The World No 32, a winner in 2018 but a semi-finalist last year, will now face Aira's older sister, Aifa in the semi-finals.
Aifa, the World No 58, reached the last four for the second time after getting past Lai Wen Li 11-5, 9-11, 11-5, 11-5.
"I do not take it easy against up-and-coming players as I have been in their position, and I know what it is like to beat your senior," said Sivasangari of Aira.
On her win, Sivasangari said: "I was not focused in the second game, but I managed to get through it and finish strongly in the third.
"Aifa is a different kind of challenge. Everyone knows she is a good player, so I've got to be ready and stick to my game plan," she added.
Top seed and defending champion Low Wee Wern finally got into action, and she had little trouble dispatching Ooi Kah Yan 11-6, 11-9, 11-7.
"I was mostly in control, although Kah Yan hit some good winners," said Wee Wern, who takes on Rachel Arnold in the last four.
"Rachel should be in confident mood, so hopefully I'll do well against her tomorrow (today)."
In the men's Premier division, joint third-fourth seed Darren Rahul Pragasam survived the longest match of the tournament by overcoming Ong Sai Hung 12-10, 12-10, 6-11, 2-11, 11-7 after 81 minutes.
Darren plays second seed Syafiq Kamal, who downed veteran Elvinn Keo 2-11, 11-5, 11-8, 11-7.
The other semi-final is between top seed Ivan Yuen and joint-third fourth seed Addeen Idrakie.
RESULTS
Men's quarter-finals: Syafiq Kamal bt Elvinn Keo 2-11, 11-5, 11-8, 11-7; Darren Rahul Pragasam bt Ong Sai Hung 12-10, 12-10, 6-11, 2-11, 11-7; Addeen Idrakie bt Siow Yee Xian 11-3, 8-11, 11-8, 11-7; Ivan Yuen bt Asyraf Azan 11-1, 11-2, 11-2.
Women's quarter-finals: S. Sivasangari bt Aira Azman 11-4, 14-12, 11-2; Aifa Azman bt Lai Wen Li 11-5, 9-11, 11-5, 11-5; Rachel Arnold bt Chan Yiwen 11-7, 11-2, 11-5; Low Wee Wern bt Ooi Kah Yan 11-6, 11-9, 11-7.