WORKERS tend to slack off on their final shift before heading away on a sunshine break.

Their attention strays, they watch the clock, they start to freewheel. Celtic fly out today for a week-long trip to Turkey and perhaps St Mirren privately thought they might have turned up in chilly Paisley with heads filled with thoughts of sun cream and beaches. The current assortment of impressive qualities shown by the champions includes focus and purpose, though. Celtic were crisp and diligent, and they buried this match with four second-half goals.

The trip to Turkey is not entirely a holiday. They will play Trabzonspor and either Ajax or Galatasaray in the four-team Antalya Cup, but they will have had plenty of relaxation and sun on their backs before fulfilling their first fixture there on Thursday.

They had two objectives at St Mirren Park and comfortably realised both. They kept yet another clean sheet and maintained their unbeaten league run. They now have seven consecutive clean sheets in the SPFL Premiership, in which they have yet to lose after 20 games. Motherwell's weekend postponement meant this comfortable win also stretched Celtic's advantage at the top.

By the 52nd minute, it was still nil-nil and Neil Lennon was periodically getting steamed up in the technical area over misplaced passes, wrong decisions or broken-down moves. By the 71st minute the dam had broken and Celtic had rushed in four goals through Charlie Mulgrew, Anthony Stokes and a couple from the class act on the pitch, Kris Commons. After a sticky first half, it became Celtic's first emphatic win since they put five past Motherwell a month ago today.

As is so often the case with Celtic their moments of greatest invention and quality came from Commons. He is one of the best pound-for-pound signings made in Scotland for years. For £300,000 he has brought invention, penetration and intelligence to Celtic, and goals. His first here was his 50th in 129 appearances. He is not in Kenny Dalglish's class but their body shapes are similar, as is the ability to shield the ball and hold off a defender via an ample backside. When he did that midway through the first half, it allowed him to slip a delicious ball into the path of Mulgrew's bursting run from midfield. St Mirren were wide open but were fortunate that Mulgrew's low shot flashed across the goal only to strike the inside of the right-hand post and rebound into Marian Kello's arms.

Commons himself came just as close a few minutes later. This time he was less Dalglish, more Cantona, floating a wonderful chip across goal to the far post but, unlike the Frenchman, clipping the inside of the woodwork rather than ruffling the net. James Forrest took a while to get into the game before beginning to hurt St Mirren on the right wing. He aggressively hit the line and pulled over a cross which almost reached Mulgrew.

The scoreline might not suggest as much, but St Mirren contributed plenty. Until half-time they gave as good as they got. John McGinn and Paul McGowan were busy in the engine of midfield and wee Adam Campbell, their new loan signing, was as eager as a spaniel. Campbell was never able to hurt the Celtic back four but he showed flashes of quality, in particular with one through ball which might have given Steven Thompson an opening. Eventually their defending could not contain the quality, and variety, of Celtic's attacks. An indication of Celtic's ability to threaten from throughout the team was evident when their opening goal was made by the right-back, Adam Matthews.

Sometimes Matthews' driving runs are let down by his inconsistent use of the ball at the end of them, but this time he drove on and sucked defenders towards him. His backheel spread further confusion among the St Mirren players and through a scrum of bodies Mulgrew got to the ball first to squeeze a low finish into the far corner. It was a really well-worked goal, and a game changer.

Stokes's goal was the 100th of his career but only his seventh in 33 appearances this season. The finish was as smooth and confident as any of his century. Joe Ledley spread the ball from left to right, playing Stokes in at the side of the box to bend a shot across Kello and inside his far post. Suddenly it was a bombardment. Kello saved from Scott Brown, then from Stokes again, before Emilio Izaguirre crossed to the far post and Commons stole in to score with a header. St Mirren were still reeling when Forrest hit the line again. The defending was poor and men were sucked towards the ball as Commons cleverly dropped off, collected Forrest's lay-off and rammed home a finish. Substitute Amido Balde had a later chance to make it five.

When Anton Brady was through on goal the St Mirren fans howled for a red card after Efe Ambrose brought him down just outside the penalty area. Only a yellow was shown. The credit went to those home supporters who had the stomach to still be there so late in the game to see it.