Robert Achema picked an unmarked Villa with a low cross and the striker made no mistake with a sweet connection that flew into the roof
The visitors would have double their lead in the 37th but Mukisa Junior failed to keep his header down
The best chance of the second half fell to substitute Brian Osumba but he blasted over the bar after good work from Mbugua on the right
Western Stima recorded their first win of the season after beating Posta Rangers 1-0 in an entertaining Kenya Premier League (KPL) match at Kenyatta Stadium in Machakos on Sunday.
Ugandan Villa Oromchan's 28th minute strike is all the powermen needed to claim maximum points. Stima remain unbeaten after three rounds, while for Rangers it's their first loss of the season.
Stima goalkeeper Samuel Odhiambo and his back four kept Stima in the game after the hosts threatened early through Eliud Lokwam, Francis Nambute and Jackson Dwang.
The first real chance fell to Nambute who found space in the 24th minute and sent a low shot but Odhiambo dived low to save.
Then four minutes later, against the run of play, Stima went ahead. Robert Achema picked an unmarked Villa with a low cross and the striker made no mistake with a sweet connection that flew into the roof.