The GPA failed to revenge on Gamtel who defeated them on penalties in the FA Cup 16 ties last Wednesday.
Striker Assan Ceesay, midfielder Modou Sarr and left-back Dodou Demba Susso were on target for the telecom giants in the 15th, 35thand 77thminutes of the game in their quest to attain their first-ever league title.
Armed Forces also beat Brikama United on the same score-line at the Banjul KG5 Mini Stadium.
Samba Kujabi and Kabba Jobe got a brace after netting for the security outfit in the 25th, 38th and 81st minutes of the game.
Elsewhere, the reigning league leaders Steve Biko were held to a goalless draw by struggling side Seaview at the Serrekunda East Mini Stadium on the same day.
Gamtel and Armed Forces are 2nd and 3rd on the table with 26 points each in seventeen games.
Real De Banjul have now dropped to 4th position with 25 points in seventeen games after dropping two vital points in their week-16 fixtures against Seaview.
Gambia Ports Authority are 7th with 21 points in seventeen games, Brikama United are 8th with 20 points in seventeen games, while Seaview are still struggling at the bottom with 17points in seventeen games.