The game was not without controversy - Kilmarnock captain Manuel Pascali was dismissed for a two-footed challenge on Nigel Hasselbaink - but Lomas chose instead to focus on his side's performance.
It was not until the 89th minute that the visitors finally made their man-advantage tell - Rowan Vine toe-poking home the winner to send Saints fourth in the SPL.
Lomas said afterwards: "It was a super win, but I must pay Kilmarnock credit for continuing to play two up front and putting us under pressure.
"I can understand the Kenny (Shiels) was frustrated after the sending off, however players know what it's like these days and you can't go into a challenge two-footed.
"It was hard to work out the response of the Kilmarnock fans after the red card.
"Nigel didn't roll about after the tackle, his boot was ripped as a result and he got up and played on before eventually having to be substituted."
Killie looked to have battled back to earn a point after Michael Nelson's 83rd-minute header cancelled out Murray Davidson's first-half opener, only for Vine to snatch the points.