Celtic began the defence of their Scottish Premier League title with a narrow 1-0 win over Aberdeen thanks to a late Kris Commons strike at Celtic Park on Saturday.
The home fans had celebrated the unfurling of the championship flag before the match but the party atmosphere soon turned flat as they were left frustrated by some resolute defending from the Dons.
With rivals Rangers banished to the third division after being condemned to liquidation, Celtic have been widely tipped to canter to this season's league title.
However, the Hoops struggled to break down a solid Aberdeen rearguard who restricted the home side to few opportunities before a howler from keeper Jamie Langfield handed Celtic the lead 11 minutes from time.
Commons, who had twice been denied by Langfield earlier in the match, received the ball back from his own short corner and fired in a low shot that the 'keeper somehow allowed to squirm past him at his near post.
It was a much-needed boost for Neil Lennon's side as they prepare to travel to Finland for the second leg of their Champions League third qualifying round tie against HJK Helsinki on Wednesday.
"We got a bit of luck with the goal," the Celtic manager admitted. "We were in control of the game without being brilliant. We defended well when we had to but going forward there was a lack of freshness about us. I am just delighted to get the win and clean sheet."
Aberdeen manager Craig Brown was disappointed with his side's defending at the goal. "They switched off momentarily and you can't do that at this level and unfortunately we lost in a soft manner," Brown said.
"I thought we merited a point at least from the game so there a big disappointment there but we can't feel sorry for ourselves."
Lennon made two changes from the midweek 2-1 first-leg win against HJK with captain Scott Brown and Charlie Mulgrew dropping out the squad and Beram Kayal and Anthony Stokes handed starts.
Aberdeen have strengthened over the summer and manager Craig Brown handed first competitive starts to new boys Jonathan Hayes, Gary Naismith and Niall McGinn, with the latter coming up against his former club.
The game began at a frenetic pace but the home fans had to wait until the 10th minute for their first chance when Joe Ledley held off two Dons defenders in the box only to see his shot-cum-cross smothered by Langfield. Commons and stand-in captain Georgios Samaras also threatened in the opening period but the Hoops failed to make a first-half breakthrough.
Aberdeen began the second period on the front foot and, when the Hoops defence failed to deal with a Hayes corner, Scott Vernon scooped a shot just over the bar.
Victor Wanyama then saw a shot fly wide but the visitors were restricting Celtic to long-range chances and Langfield stretched to stop a thunderous Commons strike from 25 yards sneaking in.
But, just as it looked like Celtic weren't going to find a way past the Dons' rearguard, Langfield's error gifted Commons the goal that decided the game.
Elsewhere, Hearts became the season's first SPL leaders with a 2-0 home win over St Johnstone, who had Gregory Tade sent off, thanks to a John Sutton penalty and a late David Templeton strike.
Darren McGregor scored an injury-time equaliser for St Mirren in their 2-2 draw with Inverness Caledonian Thistle, while newly-promoted Ross County opened their SPL account with a 0-0 draw with Motherwell and Kilmarnock against Dundee also ended goalless.