Kilmarnock won their first match in nine league outings with a fine performance against Celtic.
On-loan Aberdeen striker Chris McGuire opened the scoring with seven minutes of the second half played after Mehdi Taouil played a neat cutback.
Celtic's new signing Robbie Keane was denied by a series of Cammy Bell saves.
A resolute Killie denied a string of chances and held out to claim three points at home to Celtic for the first time in nine years.
Keane made his first start under Celtic manager Tony Mowbray was joined in the starting 11 by Diomansy Kamara, while the fit-again Glenn Loovens and Lee Naylor were recalled and Scott Brown featured on the bench following his prolonged ankle injury.
Killie handed a debut to new loan signing Chris Maguire, while Tim Clancy made his first appearance since September.
After seven minutes of intense pressure from Celtic, Ki Sung Yong blasted in a powerful free-kick from 25 yards out that Killie keeper Bell turned around the post.
A few minutes later, Liam Kelly tested the Celtic keeper Artur Boruc with a shot from distance that the Polish stopper almost fumbled.
Kilmarnock seemed unfazed by the early Celtic pressure, although Gary Hay was forced to clear a Kamara header off the line in the 21st minute.
The on-loan Senegal striker then blasted in a driving right-footed shot from the edge of the box two minutes later that inched past Bell's left-hand post.
Keane's first attempt on goal arrived on the half-hour mark, but the Republic of Ireland captain curved the ball towards the outside of the post and Bell helped it out for a corner.
Four minutes later, the on-loan Spurs striker tried his luck with a lob, but missed the target then was kept out by Bell with a fine double-save from close range.
Following the break, Kamara sent a glancing header looping over the bar, but the home side broke the deadlock with seven minutes of the second half played when Taouil played a neat cutback inside the Celtic penalty area and the on-loan Dons striker McGuire buried the ball past Boruc.
Kilmarnock continued to pile on the pressure and Celtic show signs of strain, with Aiden McGeady and Landry N'Guemo soon finding their names in the referee's book for a sequence of harsh challenges.
Shortly after the hour mark, Marc-Antoine Fortune pivoted on the six yard line and made for the Killie goal with Bell making the block and denying the Frenchman a chance to equalise.
Fortune glided in an inch-perfect cross from the right-hand side that Keane latched on to and sent goal-bound, but Bell came to the rescue and Celtic remained frustrated.
With less than 20 minutes of the match remaining, Connor Sammon squandered an opportunity to set up Kevin Kyle when he blundered a cross-field pass to the big striker and a rare second-half Killie attack fizzled out.
Loovens was unlucky not to reach the target for Celtic with a header from Ki's corner moments later.
The South Korean midfielder volleyed in from a clearance as the minutes ticked away, but his shot shaved the left-hand post.
Jamie Hammil brought out the best in Boruc in the final five minutes as Killie pressed to finish the game, but the Celtic keeper was up to the challenge.
Keane tested Bell at the other end 60 seconds later and seemed certain to score, but the Killie keeper pulled off a fantastic save with his feet.
Substitute Brown leapt above the Killie defence to nod in from six yards, but again Bell was on-hand to deny.
Jimmy Calderwood on the Celtic Post Match... "It's been a long time and it was wonderful. Celtic started strongly and Robbie Keane was causing us all sorts of problems and we never really got into the game. But we changed it and got a grip on it, but they're so dangerous on the counter-attack.
Our keeper made a couple of great saves and we didn't make Artur Boruc work too hard, but we got the goal, which was vital and we hung on to win the game. I told my players they were playing against a good side and you need to get the breaks, and we're lucky enough that that's how it worked out.
Cammy Bell was fabulous. Sometimes you feel the script is written, but we changed the script."
Kilmarnock: 13Bell, 02Clancy (Kiernan 73), 03Hay, 06Ford, 07Bryson, 08Pascali, 10Taouil (Sammon 62, 22Kelly, 23Hamill, 16Kyle, 28Maguire (Severin 80),
Substitutes: 21Robinson, 04Fowler, 14Old, 29Kiernan, 11Invincibile, 25Severin, 18Sammon.
Attempts on target
Attempts off target