Raith Rovers 0-3 Celtic: Last eight for Celtic CELTIC were made to work much harder in testing Kirkcaldy conditions than the final scoreline suggests to book their place in the last eight of the Scottish Cup. Scorers: Commons 56 (pen), Forrest 83, Mulgrew 86 After a goalless first half, it took a contentious penalty kick earned and converted by Kris Commons to give Celtic the edge before two outstanding late goals from James Forrest and Charlie Mulgrew made the tie safe. But if the ultimately comprehensive nature of the result does not reflect the admirable contribution of Raith Rovers to an absorbing contest, there was also no doubt Neil Lennon's side fully merited their passage to the quarter-finals. With their treble ambitions having evaporated in League Cup semi-final defeat to St Mirren at Hampden seven days earlier, this was an occasion when the manner in which a positive result was achieved was of secondary consideration to the Scottish champions. They duly had to come to terms with a heavy playing surface at a ground Celtic had not visited since Paolo Di Canio scored in a 1-1 Premier Division draw back in 1997. Those heady days of top-flight football are a fading memory for Rovers but they can take pride in their efforts yesterday. They will also enjoy a much-needed boost to their finances with the revenue accrued from live television coverage of the tie. Celtic could not be accused of lacking purpose in their work as they looked to avoid a second successive Sunday afternoon domestic cup upset. But for all that they hemmed Raith Rovers into their own half for most of the first half, the SPL leaders struggled to find the inventiveness or penetration necessary to upset a disciplined and diligent defensive set-up. It might have been a more comfortable day for Celtic had they been successful in what appeared a strong appeal for a penalty kick after just six minutes. Mulgrew's cross from the left was only partially cleared by Rovers central defender Laurie Ellis, the ball then appearing to be handled by Eddie Malone before the left-back booted it to safety. Referee Steven McLean was unmoved by the voluble claims of the visiting players and Rovers made the most of that let-off to frustrate Celtic for the rest of the opening 45 minutes. As they toiled to find a way in behind the Rovers backline, Celtic were largely restricted to efforts from distance. Rovers goalkeeper David McGurn dealt with them all comfortably, beginning with a low drive from Mulgrew which he clutched confidently in the 14th minute. Celtic had another penalty shout six minutes later, although on this occasion it seemed more optimistic as Adam Matthews suggested his driven cross from the right had been handled by Ellis. Rovers leading scorer Brian Graham was an isolated figure in his team's understandably cautious system, but on the rare occasions that he managed to get involved he displayed a neat first touch and good awareness of how to make the best of his limited options. Counter-attacks from Rovers were few and far between, but right-back Jason Thomson dispossessed Joe Ledley to embark on one raid which had the home fans on their feet. Thomson's 50-yard dash from his own half was ended by Ledley's recovery challenge in the Celtic penalty area which brought half-hearted claims for a spot-kick from some of the Rovers players. Celtic almost took the lead in freakish fashion when an inswinging Mulgrew corner from the right eluded everyone in the six-yard box and struck McGurn's right-hand post. It was a rare moment of uncertainty in the home defence. An increasingly emboldened Rovers side began the second half brightly, causing considerable uncertainty in the Celtic rearguard when Allan Walker's cross from the right was narrowly missed by the lunging figure of Graham in the six-yard box. Celtic responded through the adventurous spirit of Matthews, the right-back darting forward and coming close with a well struck 20-yard shot which narrowly cleared McGurn's crossbar. The Welshman then turned provider with a superb cross from the right which Tony Watt, who had toiled to make any impact on proceedings, directed wide of McGurn's right-hand post with a twisting header. When Beram Kayal conceded a free-kick in a dangerous position with a clumsy challenge on Malone, the Rovers fans dared to dream of the moment when the tie might turn in their favour. However, although Graham smartly bent the set piece around the defensive wall, Lukasz Zaluska dived to his left to claw away what was the Kirkcaldy side's first effort on target. Before that sense of encouragement could build among the home support, Celtic made their 56th-minute breakthrough. It was third time lucky as far as penalty claims were concerned for Lennon's men, referee McLean this time immediately pointing to the spot when Commons was floored by Mensing's challenge just inside the area. Celtic have not had their troubles to seek from 12 yards in recent seasons, most recently last week when Mulgrew's failure to convert a penalty at Hampden was pivotal in their League Cup elimination. Commons got up to seize responsibility this time and the man whose coolness under pressure had seen him score the spot-kick against Spartak Moscow in December to secure Celtic's passage to the last 16 of the Champions League was just as assured here, driving the ball low and firmly into the corner of the net. But Raith were far from disheartened, threatening an immediate equaliser when Pat Clarke volleyed a Thomson cross over and then enjoying their most sustained spell of possession in the opposition half as they battled desperately to get back into the tie. But they were undone by two exceptional pieces of finishing by Celtic in the closing stages which put a far more convincing slant on the final scoreline for the tournament favourites. Substitute James Forrest, making his first appearance since Boxing Day, latched onto Gary Hooper's pass in the 83rd minute and brilliantly flicked the ball beyond his marker on the right before dinking a shot over McGurn which Ellis was unable to keep out as he slid back on the line. Three minutes later, Mulgrew found space on the left edge of the penalty area and curled a magnificent shot high beyond the despairing McGurn and into the far corner of the net. Raith Rovers: McGurn, Thomson, Mensing, Ellis, Malone; Hamill (Callachan 90), S.Anderson (Spence 74); Walker, Clarke, Smith (G.Anderson 65); Graham. Subs not used: Donaldson, Laidlaw. Celtic: Zaluska, Matthews, Lustig, Wilson, Mulgrew; Commons (Stokes 76), Wanyama, Kayal (Brown 60), Ledley; Hooper, Watt (Forrest 60). Subs not used: Fasan, Lassad.