With the ball won just inside the Chelsea half, firstly Thiago Motta and thenSamuel Eto'o fed the ball through for Milito who, with space afforded by Wesley Sneijder's presence, stepped inside John Terry and beat Petr Cech at the near post.
Moments later, a low drive from Jim Goodwin was easily gathered by Saints keeper Graeme Smith, then Collin Samuel fired over the Accies bar from just outside the six-yard box at the other end.
Bridgend benefactor Leighton Samuel bought out Pontypridd's share in the Warriors earlier this month, which he then handed over to the Welsh Rugby Union.
Mario Balotelli then struck the crossbar with a free-kick before the points were sealed in the final minute when Samuel Eto'o was left unmarked in the area to slide home a Sulley Muntari cross.