Craig Sibbald's second-half strike was enough to see Falkirk edge past Cowdenbeath 1-0 in the fourth round of the Scottish Cup.Midfielder Kudus Oyenuga wasted a decent chance for the visitors when he blazed over inside the box after 22 minutes.At the other end, Blair Alston skimmed the crossbar with a long-range effort before team-mate Rory Loy forced a good stop from goalkeeper Robbie Thomson.Sibbald then put Falkirk ahead in the 73rd minute when he made no mistake inside the box after reacting quickest to Loy's deflected shot.Substitute David Smith should have made it two for the Bairns late on but he could only fire over with the goal at his mercy.