The hosts’ Dong Duc Thang broke the off-side trap and scored the opener midway through the first half after collecting a great pass from striker Dinh Tung.
Unable to keep calm after conceding the goal, the visitors’ central fullback Dao Van Phong and striker Agostinho tackled the host players too violently and received red cards from the referee.
The hosts capitalized on the advantage of playing with more men on the field and scored two more goals, although Le Van Tan got a consolation goal for the visitors.
Hai Phong, with five points, is now in the 13th position in the 14-club league, leaving Kien Giang at the bottom after they were held 0-0 at home by Ninh Binh, who slid one place to fourth with 11 points.
Hanoi FC jumped three positions to 10th after coming from a goal down to take a 2-1 home win at the Hang Day Stadium against visitors Dong Thap, who fell two spots to seventh.
Nigerian striker Felix Gbenga Ajala scored the opener for the visitors from the Mekong Delta after 25 minutes; but Striker Cong Vinh, who didn’t score a goal in the first five rounds, found the net from a free kick to equalize the score before making a neat pass to Anjembe Timothy who scored the winner for the hosts.
The league's 2010 champions Hanoi T&T continued to lead the league with 13 points after losing 0-2 away at Chi Lang Stadium to 2009 champs Da Nang, who climbed one place to third with 11 points.
In early matches Saturday, defending champs Song Lam Nghe An climbed one place to sixth after a 2-0 win at home at Vinh Stadium over 2003-04 champs Hoang Anh Gia Lai, who remained in eighth spot.
2007-08 champs Binh Duong climbed one position to fifth after a 1-0 away win at Ho Chi Minh City’s Thong Nhat Stadium over Navibank Saigon, who fell two places to 12th.
Saigon FC remained in second place a point adrift of the leaders after being held 1-1 away by hosts Thanh Hoa, who climbed one place to 10th.