Gary Hooper grabbed four goals against Raith Rovers as Celtic eased into the quarter-finals of the Scottish Communities League Cup.
Dylan McGeoch cut the ball back from the by-line and Hooper fired Celtic ahead after 12 minutes.
Allan Walker's deflected drive off Thomas Rogne put the First Division side level before the half hour.
Hooper fired his second from a James Forrest cross nine minutes later and added two more after the break.
Celtic manager Neil Lennon had taken the chance to give midfielders Beram Kayal and Joe Ledley some game time following their lengthy absences through injury and give recent signing Efe Ambrose his first start in midfield amid six changes to his side.
But, with the top tier of Celtic Park closed, most of the noise in the low-key early stages came from the travelling supporters.
They were encouraged by their side's efforts to build from the back, but that was to be their undoing when defender Jason Thomson's pass from wide on the right touchline was cut out by Forrest.
The winger sped forward and switched the ball to McGeouch whose low driven cross was steered in almost casually from close range by Hooper.
Rovers goalkeeper David McGurn saved from McGeouch and Hooper, while Rogne smashed an effort off the post as Celtic threatened to run riot.
Somewhat out of the blue, Rovers were level when Walker gathered 20 yards from goal and his drive took a nick off defender Rogne before spinning over goalkeeper Lukas Zaluska and in off the post.
Kayal scooped a Charlie Mulgrew corner over the bar from a few yards out, but the groans in the home support turned to relieved cheers when Forrest's cross into the middle was confidently converted by the unmarked Hooper.
The Kirkcaldy side should have levelled for the second time in the 50th minute when Walker set up Brian Graham with a fine cross, but the big striker did not get enough on his header from eight yards and the ball went wide.
That was the last hope Rovers had of pulling off a shock as Hooper grabbed his hat-trick in the 58th minute when he finished off a fine move involving McGeouch and Adam Matthews by drilling an angled shot past McGurn.
On the hour mark, the Englishman tapped in from almost on the line after Kayal's shot lacked the power to see him on the scoresheet.
A Forrest shot struck the post and McGurn turned a powerful Matthews drive over the bar, but Celtic had already done enough for a comfortable win.
Celtic manager Neil Lennon: "Very pleased. Great performance going forward at times.
"Gary Hooper is a phenomenal goalscorer - he's a phenomenal player - and I'm delighted for him.
"He was the stand-out player for us with four great finishes and his general play as well.
"Ambrose's debut was as good a debut as you will see - composed, good pace to his game, played very well.
"He can play in a number of positions, but tonight in midfield we thought it was a good time to bed him in and it looked like he'd played here for years.
"Dylan started the game really well and James, once he's in full flow, is as good as any winger in Britain. Forrest, I think, is an exceptional talent and we saw that again.
"We've always wanted to play them together and it's given us food for thought."
Raith Rovers manager Grant Murray: "It was always going to be a difficult task and, when you go behind early, it does make it an uphill battle.
"But, credit to the guys, they got themselves back in the game and probably had a chance after that.
"But, when Celtic get the second and third, it does make it difficult.
"But my players can come away from here heads held high. They gave it everything they had."