They left as they arrived.

The title celebrations at Pittodrie had begun long before yesterday's game had kicked off.

By the time the Celtic players left the pitch, their 100 per cent league record over Aberdeen still intact after a 1-0 win, their supporters and the lingering Hoops players were in party mode.

Not even a pie thrown at skipper Scott Brown after he had scored Celtic's only goal could tarnish the joy among the travelling support.

The 'Ronny roar', contrived or not, was met with welcome approval at the end of a 90 minutes that will not pass off as a vintage performance, but rather, one in which Celtic showed the necessary endeavour, drive and just that little bit of quality to take the three points.

Deila's celebration was in stark contrast to Celtic's last visit to Pittodrie, back in November, when a last-gasp winner gave birth to the now trademark celebration.

That afternoon was about sheer relief as the Norwegian celebrated a watershed moment in his Hoops career

Yesterday's was different. His acceptance from the Celtic support has been absolute for some time now, but the challenge is where he takes the club from here. Europe calls and, with it, an entirely different kind of test awaits.

Domestically, Aberdeen pushed them far longer than anyone would have anticipated this season, but until they can go up against Celtic and come away having hurt them by taking points, then Kris Commons' assessment of their title challenge will remain accurate.

In the aftermath of this encounter, Derek McInnes remarked that he felt as though his side "really rattled them" at times but, ultimately, if Aberdeen are to sustain what they have built this term then they need to be able to go up against Celtic and come away with something other than pride.

On a different day, they might have taken something from Celtic.

The pace of Jonny Hayes was a source of consternation for the Parkhead side throughout the game - the fact that both Virgil van Dijk and Jason Denayer shone for Celtic underlines how much Aberdeen made Deila's men work for the points.

They gave the Parkhead side a guard of honour, but that was where the respect for Celtic finished. And for all that there was nothing at stake for either side in the game, there was plenty of niggle on show.

Aberdeen flew into the game, keen to make an early mark on proceedings and it was Hoops stopper Craig Gordon who was by far the busier of the two keepers.

It has been an impressive campaign for the Celtic goalie who pulled off a couple of decent stops and, in that opening half, he had to be alert on a number of occasions.

He had to pluck a ball from the toe of Mark Reynolds after the Dons had caused consternation in the Hoops defence, while a fierce free-kick from former Celt Barry Robson was also well held by Gordon.

It took Celtic until the half-hour mark to really come into the game and Stefan Johansen ought to have seen them in front at the break.

A fine ball from Emilio Izaguirre sent SPFA Player of the Year Johansen scarpering clear, but his effort was too wide of the upright.

Similarly, Darnell Fisher, after being teed up by Leigh Griffiths, should really have done better rather than scoop his attempt over the bar. The difference between the sides was that little bit of quality.

Hoops skipper Brown often dominates headlines for the snarling manner in which he can go about games, but his contribution to Celtic this season cannot be overplayed.

It was the return of Brown to the team in those difficult, early days of Deila's reign that turned things around for the Norwegian, and it was his vision and energy that proved to be the difference at Pittodrie yesterday.

The midfielder slid in to dispossess Barry Robson on the edge of the Celtic box before haring his way forward and slipping the ball wide to Griffiths, who then fed Stuart Armstrong.

The midfielder skipped into the Aberdeen box and fired a low ball across the six-yard line for Brown, who had run the length of the park, to slide in and convert.

He enjoyed his celebration, hamming up his role of the villain in front of the Aberdeen fans, one of whom was moved enough to lob a pie in his direction.

"That is a compliment," said Deila, in reference to the abuse Brown takes from opposing fans. "He loves winning and he is so good with his team-mates. We need strong characters to play at this football club and he is one of them."

A fine double save from Dons keeper Scott Brown denied Griffiths and then Commons from adding to Celtic's lead, although a Hayes cross that was headed wide by Lawrence Shankland as the game drew to a close could have given Aberdeen a leveller.

Celtic, though, held on for the win.

There are just two games remaining now as they head towards the finish line and prepare for the bigger challenges that lie in wait this summer.