Queen of the South strengthened their grip on a Scottish Championship play-off place with a 1-0 victory against top-four rivals Falkirk at Palmerston Park.Derek Lyle scored the only goal of the game midway through the first half to give the Doonhamers a third straight league win and moved James Fowler's men four points ahead of their opponents, with a game in hand.Blair Alston and John Baird threatened for Falkirk early on but Lyle netted from Michael Paton's pass after 22 minutes.The Bairns tried to get level but Alston headed wide and home goalkeeper Alexander Clark parried shots from both Craig Sibbald and Luke Leahy in the second half.