Falkirk were determined to make amends to their travelling fans for last week's Cup debacle against Clyde, and almost went ahead from a Pedro Moutinho shot with only 42 seconds on the clock.
Fortunately for the home team, the Portugese under-21 international skied his drive from 18 yards with keeper Kevin Cuthbert stranded.
In the 24th minute the Bairns went ahead as the Saints succumbed to a trademark Russell Latapy goal. Dragging the ball in from the left wing, the Trinidadian outfoxed defenders Mark Baxter and Ian Maxwell as he drove towards goal. With the home defenders anticipating a pass, the 36-year-old midfielder unexpectedly scooped the ball high into the home net from the tightest of angles.
In a flurry of action as the first half drew to a close, Saints forced three goal attempts from Peter MacDonald, Kieran McAnespie and Michael Moore, but the visitors kept their heads and their one-goal lead as they went into the second period.
A Moutinho goal after 52 minutes and a Darryl Duffy penalty eight minutes from time put the game well out of Saints' reach.
Having lost the game so comprehensively, Saints were not only concerned at the result but at what looked like a possible neck injury suffered by keeper Kevin Cuthbert as he collided with teammate Kevin Fotheringham in the 52nd minute.
Cuthbert made an unsuccessful attempt to stop Moutinho from getting on the end of a superb Duffy left-hand cross. The ball broke free and the No 9 thudded it home from close range. Cuthbert was knocked out and had to be stretchered from the field.