IT wasn't difficult to imagine the smiles spreading across Croatian faces as they watched Celtic win only their second away game in the SPFL Premiership this season.

This was the sort of flawed, forgettable victory which could give sustained satisfaction only to those monitoring it on behalf of Dinamo Zagreb, who Celtic must try to overcome in the Europa League on Thursday night.

Against Motherwell eight days ago Celtic improved only when Scott Brown and Kris Commons came on as half-time substitutes. In Paisley the team looked more dangerous only when the formation changed to 4-4-2 after an hour. Is Ronny Deila to be criticised for getting his selection or his formation wrong in the first place? Or should the manager be given credit for assessing the problems and knowing what was necessary to deliver an improvement?

What is beyond question is that Deila does not put his faith in a small, settled, unchanging group of players. He has been unfortunate with injuries and has made no secret of the fact he likes to rotate his squad but, even so, to have used 28 players in only seven league games is excessive. Deila wants to cement partnerships and relationships within his team but that can come only with a spine of the same players being used week in, week out and learning each others' positioning, movement and instincts.

They were poor against St Mirren (to his credit Deila did not try to airbrush that fact, his assessment after the match was cold and critical). Possession was given away far too cheaply. Players stood waiting for a ball to reach them rather than anticipating that it would be intercepted. St Mirren's rugged competitiveness kept them in the game although their limitations meant they could not do enough with the ball.

They offered too little threat to the Celtic goal. If Deila's players are as wasteful with the ball on Thursday night, Dinamo Zagreb will be far better equipped to punish them.

"We need to step up but it is at home so that will help us," said Stefan Johansen, the midfielder whose form this season has not been a match for his effective opening few months at the club. "The most important thing against St Mirren was the three points and on Thursday the three points need to come. But we need to play much better. It was difficult to play our game on a sticky pitch although that is no excuse. We didn't have enough energy either.

"We need to aim for three wins at home [in the Europa League games against Dinamo Zagreb, FC Astra and Red Bull Salzburg]. At home we should aim to beat all the teams. We were disappointed not to be in the Champions League but this competition can still be good for the team."

There was much less between Celtic and St Mirren than the champions would have wished. Little battles and duels took place all over the pitch and honours were generally even.

After John Guidetti bundled the opening goal over the line - although no arguments from this observer if anyone insists that the otherwise impressive Jim Goodwin actually made the decisive connection - St Mirren equalised after Craig Gordon's first error in a Celtic shirt. His awful throw after saving a corner invited St Mirren right back on to his defenders and John McGinn's cross was converted by Kenny McLean.

Four nights before the game St Mirren had played for 120 minutes against Partick Thistle - and gone out of the League Cup - and against Celtic they began to tire near the end. Jason Naismith and McGinn had suffered from a virus last week, which didn't help them.

"The manager drilled us brilliantly and we were playing so well," said McGinn. "It just hit a stage where gaps started appearing and Celtic were getting chances. The last half an hour I was like the tin man. I hardly trained and it started to show."

They face another tough one tomorrow night, against Aberdeen at Pittodrie. McLean's goal was the first St Mirren had scored in four home league games this season but they have lost all of them. They were downed on Saturday by the one moment of quality penetration in Celtic's performance.

If the opening goal had revealed little about Guidetti other than his good positional sense, his winning goal was far more enjoyable for the supporters who were soon enthusiastically singing his name. Stokes, who had been wide on the left of midfield before being moved alongside him in attack, showed lovely awareness and touch to spot his run and thread a fine through ball. Marian Kello might have dashed to reach it first but instead he held back. Guidetti attacked the space and latched on to the ball to drill a firm low shot which squirted through Kello into the net.

Celtic's failure to land Guidetti until the closing minutes of the transfer window, meaning that he was not registered in time to play in the Europa League, looks more inexplicable and absurd with every goal he scores. He has three goals in four appearances compared to Stefan Scepovic's none in five. The Serb may come good, but for now it looks like Celtic go into Europe relying on the wrong man.