Rangers 3 Kilmarnock 0

Kris Boyd showed little mercy to former club Kilmarnock as he grabbed Rangers' second goal in the 3-0 Ibrox win which eased the Light Blues into the William Hill Scottish Cup last 16. The former Scotland striker was left on the bench by boss Ally McCoist but netted just 90 seconds after coming on as a second-half substitute. Nicky Law had given the Championship side a 19th-minute lead with his deflected opener and swept home another with a fine finish six minutes from time. It was a welcome win - their third victory over top-flight opposition this season - for under-pressure boss Ally McCoist after last week's defeat to promotion rivals Hearts. And it was also a good day for Boyd. He returned to Ibrox in the summer after a 22-goal stint with Killie last season but has struggled to repeat the lethal form of his record-breaking first spell with the club. But he wasted no time in punishing a mistake by best friend Craig Samson in the Rugby Park side's goal with the crucial second as the visitors slumped to their fifth straight defeat. Killie's last visit to Ibrox was six days after the club was plunged into administration in February 2012. Since then the Light Blues faithful have endured a living nightmare that shows no sign of relenting. Last week's 2-0 defeat at Tynecastle leaves them nine points adrift in the race for automatic promotion back to the Premiership, while their off-field woes continue to roll on with this week's news that the club lost another £8.3million in the year up to June 30. The home fans once again showed their frustrations by staying away in their droves, leaving a meagre crowd of just 14,412 to watch the action. Early sniffs at goal from Rangers' Lewis Macleod and the visitors' Rory McKenzie offered hope of an open affair. But it was not until the 15th minute that a genuine attempt on target was registered. Defender Bilel Mohsni dived in on McKenzie down on the right touchline but the Killie winger skipped past the challenge before pulling the ball back for Alexei Eremenko. The Finnish playmaker's shot did not look threatening until it skipped off Lee McCulloch's boot and squirmed a fraction wide with Steve Simonsen wrong-footed. But it was Rangers who got the breakthrough. Darren McGregor launched a long throw into the box which Killie failed to clear further than Fraser Aird on the edge of the box. The Gers winger had to shove referee Brian Colvin out the way before stabbing the ball back to Law, who saw his right-foot sweep deflect off Sammy Clingan's brow on its way into the top corner. The goal sparked Rangers into a sudden burst of industry. Macleod stung the hands of Samson with a 25-yard strike while Kenny Miller claimed for a penalty after Ross Barbour slid in on him just as he was about to pull the trigger. The right-back came from the wrong side but Colvin correctly judged that he took the ball. Samson then tipped away Ian Black's grass-cutter while Clingan's under-cooked header back to the keeper almost put Kenny Miller in, but Killie made it to the break without any further losses. Allan Johnston's team were livelier after the break, with Tope Obadevi giving McGregor problems down the left. But Rangers should have put daylight between the teams on 58 minutes. Aird danced past Chris Chantler before whipping a cross to Macleod at the back post, but the Scotland Under-21 cap ballooned his shot high into the Copland Road stand. Jon Daly found himself through on goal with 25 minutes left but pace was never one of the Irishman's strongest attributes. His decision to play in partner Miller - rather than press forward himself - drew a huge groan from the crowd, especially when his pass failed to find its target. The former Dundee United frontman could have little complaint when he was replaced soon after by Boyd - who rubbed his team-mate's nose in it by taking just 90 seconds to make his mark. Aird's corner was met by McCulloch but Samson should have gathered it. His spill though fell straight at the feet of former Rugby Park colleague Boyd, who showed little sympathy by ramming the ball home at the near post. Law then put the seal on the win as he collected Foster's pass from the left before curling a delicious finish past the helpless Samson.