Any followers of Scottish football still unconvinced that Celtic will retain, and retain comfortably, the SPL title in the coming season doubts would have seen their doubts extinguished by this rout.

Despite being denied the services of nine first- team players, the Parkhead side brushed their opponents aside effortlessly in a fixture in the Highlands they have traditionally struggled in.

With half a foot in the group stage of the Champions League and half an eye on the game with Helsingborgs on Wednesday night, manager Neil Lennon erred on the side of caution.

He refused to take a chance with Scott Brown, Kris Commons, Thomas Rogne and Georgios Samaras, all of whom were nursing knocks, and started with several fringe players and youngsters. Mikael Lustig, Kelvin Wilson, Filip Twardzik, Paddy McCourt and Tony Watt, a quintet whose involvement in competitive action is sporadic to say the least, all found themselves involved from kick-off.

It mattered not a jot. From the moment Willie Collum got the match under way, Celtic controlled proceedings. They went ahead in the fourth minute when Victor Wanyama headed home an inswinging Adam Matthews corner and did not look back. The accomplished display, at a venue where Celtic had won on just five of their previous 10 visits, served to highlight the considerable strength in depth Lennon has at his disposal.

"It was a great performance from start to finish," he enthused afterwards. "They were superb from the moment the whistle went. The two young lads who came in did exceptionally well and the two frontmen dovetailed beautifully."

Indeed, Twardzig, the slight, skilful Czech midfielder, was a revelation. Watt, playing up front alongside Gary Hooper, suggested all the plaudits he received for his goalscoring debut against Motherwell last season were justified.

That pair combined well for the Celtic's second goal in the 25th minute. Twardzik supplied Watt on the left flank,and the striker skinned Simon King, bore down on goal and curled the ball expertly beyond Ryan Esson. Strong and direct, the 18-year-old still had work to do to net after beating his marker. He showed admirable composure for one so young playing at this level to do so. The future is indeed bright for the powerfully-built forward.

"He gives us something different," his manager said. "He is a physical presence, is prepared to run at people, does a lot of unselfish running. He was full of life and was a handful for two very strong centre-backs."

In stark contrast, Terry Butcher's team offered virtually nothing up front. A speculative long-range shot from Aaron Doran in 17 minutes was the sum total of their efforts on goal in the first half. Fraser Forster, though, dealt with it easily.

Charlie Mulgrew slotted home his side's third shortly after the start of the second half with a well-worked free-kick. Matthews squared the ball to his team-mate on the edge of the Inverness area and the defender met it with a left-foot shot that gave Esson no chance.

Watt's second goal, his team's fourth, in 63 minutes was far more straightforward. Caley Thistle, by that stage run ragged, gave their teenage opponent, making his first start, time and space to bury a loose ball bobbling on the edge of the six- yard box.

With victory assured, Lennon removed Hooper, Emilio Izaguirre and Matthews, three men who will all start against Helsingborgs, and put on James Forrest, Mo Bangura and Joe Chalmers.

"It gives the squad a huge boost going into Wednesday night and gives me a lot of food for thought," admitted Lennon. "I am hoping Brown, Commons, Rogne and Samaras will all be available."

Ross Draper bagged a consolation brace for Caley Thistle in the final minutes after reacting quickly to through balls from, first, Andrew Shinnie and then Conor Pepper. However, the outcome was never in doubt. The fighting spirit his charges once again displayed is all that will have pleased Butcher. They may need that quality this season if they continue to perform in such an alarming manner.

"It could have been more than four," admitted the Englishman "We are very disappointed with the way we performed. We can play a lot better than that. It wasn't pleasant to see. It was a long 90 minutes."