All the four hosts won their V-League 21st round matches on Sunday but Binh Duong faced a hard fight at Go Dau Stadium against visitors Dong Thap.
The league's 2007-08 champs, Binh Duong launched relentless attacks from the beginning but the visitors stood firm and the first half ended without a goal.
The hosts scraped through with a solitary goal by central fullback Chi Cong after goalie Buu Ngoc lost concentration during an attack early in the second half.
The victory ensured the hosts a position in the middle of the 14-team table of the league while Dong Thap remain in the 11th spot and near the relegation zone.
Hoang Anh Gia Lai (HAGL) and Thanh Hoa also won with goals in the second half. The 2003-04 champs HAGL hammered Kien Giang 3-0 at Pleiku Stadium while Thanh Hoa beat Navibank Saigon 2-0.
At Vinh Stadium, the reigning champs Song Lam Nghe An (SLNA), who had lost 4-0 to the 2009 champs Da Nang in a make-up match on Monday, took a 5-2 victory over visitors Hai Phong.
SLNA remained in the fourth place while bottom-side Hai Phong are now only one more loss from being relegated to the second-flight First Division.
In the 21st round's early matches on Saturday, Da Nang took the top spot after a 2-0 home win at Chi Lang Stadium over Hanoi FC, while 2010 champs Hanoi T&T lost their top position after a 3-2 home defeat at Hang Day Stadium to Ninh Binh.
With 41 points, Da Nang now lead the league, two points clear of Hanoi T&T.
Saigon Xuan Thanh remained in third place with 35 points after a 2-1 home win at Ho Chi Minh City's Thong Nhat Stadium over Khanh Hoa, who are still second from bottom with 22 points.