Christine Hallasgo waves the Philippine flag after ruling the women's marathon event of the 30th SEA Games at New Clark City Stadium in Tarlac on Friday. (Roman Prospero)

New Clark City — Unheralded Christine Hallasgo pulled off an upset on Friday morning as she unseated fancied teammate and defending champion Mary Joy Tabal in the women’s marathon event of the 30th Southeast Asian Games here.

Hallasgo clocked 2 hours, 56 minutes and 56 seconds to upstage the 2016 Rio de Janeiro Olympian Tabal, who came in second at 2:58:49.

Tabal collapsed at the finish line and was taken to the medical tent.

Vietnam’s Thi Hong Li Pham submitted 3:02:52 to settle for silver.

“Malaki ang sacrifice ko dahil naiwan ko ang pamilya ko sa Malaybalay, Bukidnon,” said Hallasgo, who ran her first SEA Games marathon.

Medical personnel attend to Mary Joy Tabal who collapsed at the finish line. (Joel Orellana)

The 27-year-old Hallasgo said she did not expect to win as she just joined the national pool in July.

Indonesia’s Prayogo Agus bagged the men’s event gold in 2:26:48, Thailand’s Namkhet Sanchai was silver medalist with a time of 2:27:18 and Malaysia’s Mohamad Muhaizar clocked 2:33:08 for bronze.

Cagayan de Oro native Jerald Zabala was the best-placed Filipino, coming in fifth with a time of 2:37:20, while Anthony Nerza was sixth in 2:39:28.