There was one comedy moment in the second period at Stark's Park that summed up the kind of Scottish Cup-tie this was.

Scott Brown, obviously fresh to the fray since he was one of the few still sporting a pristine kit, was left to look a touch foolish as an attempted cross took a wicked bounce off a crater on the ground and sliced into the crowd behind the goal.

The Celtic captain may have been left to look a little red-faced, but the same complaint could not be levelled at Neil Lennon's side.

The Hoops came through what was an awkward 90 minutes, although the 3-0 scoreline perhaps belies the struggle they had at times to overcome not just Raith Rovers, but treacherous underfoot conditions.

The amount of rain that had fallen in Kirkcaldy meant the sodden turf broke up quickly, with divots and ridges on the field causing all sorts of problems.

And, as his side headed into the break with the score in this game still goal-less, Lennon must have been getting a little antsy given what happened at Hampden last weekend. Celtic, for all their possession, in the first period could find no fluency or edge to their game.

It was Kris Commons who got them out of it with a penalty shortly after the restart when he was upended, somewhat stupidly, by Simon Mensing.

After last week's outburst when Charlie Mulgrew missed from the spot and Celtic were bundled out of the Scottish Communities League Cup by St Mirren – the boss yesterday got his wish of a rematch in the quarter-final draw – Commons stepped up to convert.

From that moment, 11 minutes after the restart, Celtic did not look back.

Yet, it took until the final eight minutes of the game before they were able to put a gloss on the scoreline, with an impressive strike from substitute James Forrest and a decent curling effort from Mulgrew.

"We had to play a little bit more direct because the pitch was soft and cutting up, that made it difficult to play through midfield," explained Lennon.

"We had to be patient, I thought we controlled the tie.

"We dominated the first half without being brilliant in the final third. We felt that once we got the first goal the game would open up and that's what happened."

And while Lennon was delighted to book Celtic's passage into the quarter-final of the William Hill Scottish Cup, he would have been equally thrilled with Forrest's return.

It has been a stop-start season for the youngster who has had a run of niggling injury problems. He hadn't featured for Celtic since Boxing Day when he aggravated a hamstring injury at Dens Park yet he looked relatively fresh.

His goal, Celtic's second of the day, showed an intelligence of both movement and awareness as he headed from one end of the park to the other, exchanged passes with Gary Hooper, dinked the ball over the Raith defence and converted.

Celtic have Inverness this weekend in the Highlands but the countdown is also on to the first leg of the Uefa Champions League last 16 tie against Juventus.

Forrest is the type who Lennon will look to have involved at some stage and the priority for the player is getting as much game time in between now and then as possible.

The youngster was one of the most consistent performers last term but hasn't quite been able to find that same level simply because his season has been interrupted by injury. Forrest's agility, his creativity and his unpredictability make him a considerable asset when fully fit.

"James is a wonderful player and he makes us better," Lennon said. "He's been dying to get back into the team and, in his last three appearances, he's scored two goals.

"In each appearance he's been marvellous, he's worked really hard in training and you can see what a great player he is."

LENNON added: "He has got so much ahead of him, he's a throwback to the players that we like, those in the tradition of the club like Jimmy Johnstone and Davie Provan. James gets people off their seats."

Lennon's big hope now is that those Celtic players who are off on international duty for Gordon Strachan's first game as Scotland manager this week come back unscathed since the last thing he needs is any bodies in the treatment room.

The biggest thing for Celtic is keeping everyone fresh and fit and making sure that they go into the game against the Italian giants in a positive frame of mind.

Yesterday's result enables them to put last week's League Cup defeat firmly out of sight, although the evaporation of the Treble ambitions will take some time for Lennon to fully absorb.

The game against Terry Butcher's side this weekend in Inverness has the potential to be a sticky one for Celtic with so many players away on international duty with their respective countries.

Going into the Juve tie with a positive mindset will be the aim.