National Cup champions Navibank Saigon were dethroned on their home ground at Ho Chi Minh City's Thong Nhat Stadium after losing 3-4 to underdogs Binh Dinh on Sunday.
The strikers of the hosts displayed pretty good performances, but the defenders made terrible mistakes, making it possible for the visitors to take the win.
The victory made Binh Dinh the only team from the second tier to be among the final eight teams in the quarterfinals this season.
In other action, Thanh Hoa came from behind to beat Can Tho, while Da Nang beat Lam Dong 3-1 in a penalty shootout after a 1-1 draw in the official 90 minutes.
Ninh Binh beat Hanoi FC 2-1, while Hanoi T&T beat Vicem Hai Phong 2-0. Kien Long Bank Kien Giang defeated Hoang Anh Gia Lai 2-1, and V-League champs Song Lam Nghe An (SLNA) beat Dong Thap 2-1.
In an early match on Saturday, Saigon FC took a 3-2 home win over Khatoco Khanh Hoa at Thong Nhat Stadium.
In the quarterfinals on the January 28 and 29, SLNA will clash with Ninh Binh, while Saigon FC will take on Thanh Hoa. Binh Dinh will play Hanoi T&T, and Da Nang will encounter Kien Giang.