Watt a double for Tony
Tony Watt scored a double on his first Celtic start as Neil Lennon's injury-hit side swept to a 4-2 victory at Inverness.
The 18-year-old produced a brilliant piece of skill, a good turn of pace and a composed finish in the 24th minute to add to Victor Wanyama's early headed opener.
Charlie Mulgrew fired Celtic three ahead just after the break and Watt was on hand to make it 4-0 in the 64th minute.
However, Celtic switched off the final 10 minutes and Ross Draper scored two consolations.
Celtic could have been further out of sight by then with Watt showing more of the promise that he first announced in the Celtic first team when he scored a double against Motherwell within six minutes of coming on for his debut.
The win came despite Celtic being forced into six changes following their Champions League win over Helsingborg on Tuesday. Thomas Rogne, Scott Brown, Georgios Samaras, Kris Commons, Beram Kayal and Joe Ledley all dropped out through injury.
But Wanyama returned from suspension to dominate the central midfield with another teenager, Filip Twardzik, showing some good touches alongside him.
Mikael Lustig, Kelvin Wilson and Paddy McCourt were also handed starts as Lennon utilised his squad in their fourth consecutive away game following a Philadelphia friendly against Real Madrid, a draw against Ross County and the win in Sweden.
Inverness were without suspended midfielders Richie Foran and Owain Tudur Jones and a first game against Celtic proved the steepest of learning curves for the summer signings in their starting line-up - defenders David Raven, Simon King and Gary Warren plus midfielder Draper.
Celtic showed no signs of travel-weariness as they took the game by storm.
Gary Hooper nutmegged King and had a driven shot parried by Ryan Esson and Celtic scored from the resulting fourth-minute corner.
Adam Matthews, playing in right midfield, drilled a corner on to the six-yard line and Wanyama rose above a crowd of bodies to head into the roof of the net.
Watt then signalled his threat when he cut in from the left and fired over and Mulgrew then hit the frame of the goal after curling a 25-yard free-kick towards the top corner with Warren able to head the rebound off the line under pressure.
Inverness took 17 minutes to get anywhere near Fraser Forster's goal with the Celtic keeper parrying Aaron Doran's 35-yard strike.
Caley Thistle improved but they were caught on the break when Twardzik played the ball forward for Watt. The former Airdrie striker flicked the ball through King's legs, raced clear and guided the ball into the corner from 18 yards.
Inverness responded with a good move down the left but Andrew Shinnie guided Doran's cross beyond the far post.
Celtic were soon back on the attack and Watt was inches from converting Twardzik's low cross after McCourt and Hooper had opened up the hosts.
Celtic started the second half like they had the first as Watt and Hooper continued to torment Warren and King. The teenager showed skill and pace to get away from both to set up Hooper, whose low shot hit the legs of Esson.
Celtic netted within three minutes of the restart following a free-kick 18 yards out on the left. Matthews rolled a square pass into the box and Mulgrew escaped Shane Sutherland's attentions to drill the ball into the bottom corner.
Watt, who set up the late equaliser against County last weekend, almost scored from the tightest of angles after some great close control.
Substitute Josh Meekings and Andrew Shinnie had shots straight at Forster before Celtic went four up in the 64th minute.
Emilio Izaguirre ran on to McCourt's flick before leaving Nick Ross in a heap and his back-post cross found Matthews in space. The Welshman could not get a clean shot in but he managed to steer the ball into the path of Watt, who steered the ball home from six yards.
Caley Thistle's pain was compounded as Ross went off with a shoulder injury.
Watt had a half chance for a hat-trick but scuffed his shot before Lennon introduced another 18-year-old, Joe Chalmers, for Izaguirre.
Caley Thistle grabbed a consolation in the 82nd minute when Draper ran on to Shinnie's through ball and finished low inside the near post.
Gavin Morrison soon wasted another good chance and Draper grabbed his second from close range after Forster had parried his initial effort following Doran's cross.
Inverness CT 2-4 Celtic: Match Report - view commentary, squad, and statictics of the game as it happened.