Motherwell put three past Celtic
Gary Hooper opened the scoring for the visitors in the 39th minute before Henrik Ojamaa levelled seconds before the interval.
Motherwell's top scorer Michael Higdon put the home side ahead from the spot five minutes into the second-half after Celtic defender Charlie Mulgrew was adjudged to have fouled Ojamaa just inside the box.
Five minutes later right-back Mikael Lustig headed a Tom Hateley cross against his own post with the luckless Hoops keeper Fraser Forster seeing the ball come off him and into his own net.
Motherwell moved on to 60 points, nine ahead of third-place Inverness with three games remaining and it would take a remarkable collapse to deprive the Steelmen of second spot but Europe is guaranteed.
There should be no surprise that Celtic looked ropey at times.
Having clinched the SPL title last week against Inverness, and with one eye on the early return in the summer for Champions League qualifiers, Hoops boss Neil Lennon allowed Kris Commons, Joe Ledley, Efe Ambrose and Kelvin Wilson to go on holiday.
Among the six changes to the visitors' side there were rare starts for defender Thomas Rogne, midfielder Tom Rogic and striker Tony Watt.
The game was delayed five minutes for running repairs to an advertising sign on the roof of one of the stands and then the home side applauded Celtic on to the park in tribute to their title win.
Watched by Lennon sitting in the stands serving the second of a three-match touchline ban, Watt flashed a drive over the bar from the edge of the box in the first minute.
Celtic had a decent chance in the 17th minute when stand-in skipper Georgios Samaras set up Beram Kayal at the edge of the box but the Israel midfielder's strike, powerful as it was, went straight to Well keeper Darren Randolph.
A trademark Mulgrew free-kick from 30 yards on the half-hour mark had Randolph throwing himself to his left to parry clear but three minutes later he made an even better save from Hooper, who had escaped Stevie Hammell at the back post to latch on to Rogic's cross.
It looked like the former Scunthorpe striker would have the easiest of tasks knocking in from three yards but Randolph brilliantly blocked the volley and the Steelmen breathed again.
There was a claim for a penalty at the other end seconds later when then ball looked to have come off Rogne's arm from a Keith Lasley flick but referee Euan Norris was having none of it.
Celtic's opener came when Watt sped past Simon Ramsden down the left and took advantage of Randolph coming too far off his line to knock the ball over to the unmarked Hooper.
The striker's header came off the crossbar before he gathered the rebound and knocking it over the line.
Motherwell looked rattled but were level when Lasley played in Ojamaa who went past Mulgrew with ease and before Lustig could intervene, he drove low past Forster and in at the near post.
It was an encouraging end to the first-half for Stuart McCall's men and there was only five minutes gone in the second-half when Mulgrew clashed with Ojamaa in the Celtic box and Norris pointed to the spot.
Higdon confidently slammed the penalty high past Forster for his 25th SPL goal of the season and the keeper's misery was compounded five minutes later when Lustig inadvertently put a searching cross from Hateley against his own post with the ball rebounding off the stopper and into the net.
The game stretched rather dramatically thereafter.
The home defence looked as fragile as Celtic's but in the 63rd minute Forster had to stretch to make a good save when Chris Humphrey's shot deflected off Mulgrew and looked like looping over him, with the Hoops defender completing the clearance.
The Fir Park side had a great chance to increase their lead in the 69th minute when Ojamaa sent McFadden racing clear with a pass that cut open the Hoops defence but, with Humphrey looking for the cut-back, he drove straight at Forster, who made another decent save from Higdon's low drive from the edge of the box moments later.
The game petered out in rather ramshackle style with Celtic squandering a series of half-chances and substitute Anthony Stokes, on for Samaras, hitting the post but the home side deserved the cheers they got from their fans at the final whistle.