Martin O'Neill's men wrapped up their third Bank of Scotland Premier League championship in four years with a controversial 1-0 victory at Rugby Park.

Celtic were hurting after their UEFA Cup quarter-final exit to Villarreal on Wednesday night, but Stilian Petrov's 32nd-minute goal moved them an unassailable 16 points clear of fierce rivals Rangers at the top of the SPL.

But while there is nothing contentious in the way they have regained the throne, today's victory over a much-improved Kilmarnock would have upset manager Jim Jefferies, whose side were denied a 16th-minute opener from Kris Boyd after referee Mike McCurry had saved Bobo Balde further humiliation after penalising Eric Skora for a foul on him.

The defender kept his place in the side despite his mistake in midweek which lead to Villarreal's opening goal.

But Joos Valgaeren was missing after his blunder as O'Neill made three changes with Robert Douglas, Johan Mjallby and Paul Lambert replacing David Marshall, Liam Miller and the Belgian.

There was also a change of linesman, which delayed kick-off for 10 minutes, when a George Drummond was pulled from the crowd to replace Willie Dishington, who had suffered a nose bleed.

But despite the despair of midweek and championship loss here on the final day of last season, Celtic's weary team did not take long to find their rhythm, and some of their quick-fire passing left Kilmarnock chasing shadows - much like they had done themselves in Villarreal.

Stanislav Varga should have put the champions ahead in the eighth minute when Jackie McNamara's throughball found him onside, but his first-time shot flew wide.

At the other end Balde was lucky not to get punished for another bad error in the 16th minute.

He gave the ball away in the box and Boyd blasted the ball home, only for McCurry to disallow it after deeming that Skora had pulled the defender back.

Neil Lennon and Jefferies exchanged angry words in the 25th minute when the fiery midfielder kicked the ball into the dug-out after Larsson had been left in a heap by the impressive Stephen Murray and the Kilmarnock boss launched the ball back at him.

But some desperate defending by the home side again denied O'Neill's men the lead a minute later.

McNamara nonchalantly flicked the ball over the top of the defence to Petrov, but his shot was blocked by Colin Meldrum, and Greer raced back to clear Stephen Pearson's follow-up off the line.

Kilmarnock still looked threatening on the break and Skora sent Murray away and he would have tested Douglas, but for a last-ditch double challenge from Varga and Didier Agathe.

They paid the price for those wasted chances as Celtic went up the other end and set themselves on their way in the 32nd minute.

Larsson flicked the ball into the path of the lively Petrov and he held off the challenge of Greer to poke the ball past Meldrum from eight yards.

Celtic would have extended their lead in the 35th minute but for a desperate blocking tackle from Locke on McNamara, six yards out, after good work from Lennon and Henrik Larsson.

Meldrum was the next man to keep Kilmarnock in the game as he dived full stretch to push Larsson's free-kick around the post after Greer had fouled Petrov outside the box.

But the home side should have pulled themselves level a minute before the break when Skora's effort flew to Boyd, just seven yards out - but he blazed his volley wide with Douglas and the Celtic defence again all over the place.

The Scotland international goalkeeper then did well to hold Hay's long-range free-kick which took a deflection on the way through.

Further baffling decisions by the referee continued to incense the Kilmarnock defence before Danny Invincibile fired a well-struck volley just past Douglas' post.

McNamara thought he had secured the three points in the 57th minute with a volley into the net, from Agathe's cross, but Drummond flagged Larsson offside.

Lennon got himself in the referee's notebook on the hour after seeking retribution for a foul by James Fowler, who was also yellow carded.

Miller came on for Agathe in the 70th minute and almost scored three minutes later, but Meldrum acrobatically turned his 20-yard shot around the post.

The home fans were calling for a penalty in the 75th minute, however, but McCurry was right this time as Douglas booted the ball clear before clattering Boyd.

Petrov was looking for his second goal of the game with two minutes remaining, but Meldrum did well to hold his long-distance drive.

The Bulgarian captain, however, had already sparked wild celebrations and made a piece of history by scoring the goal which gave Celtic their third championship in four years.

Spain and last season's end-of-season disappointment was now a distant memory.