Second division part-timers Arbroath scored a late goal to shock Scottish Premier League leaders Celtic as the part-timers earned a famous Scottish Cup fourth round replay with a 1-1 draw at Parkhead.
With one eye on Wednesday's crucial UEFA Champions League fixture against Spartak Moscow, Celtic boss Neil Lennon made sweeping changes to his side with only two players from the midweek win over Hearts starting.
However, his makeshift side, which still contained six internationals, struggled to create any meaningful chances before a ridiculous own goal handed them a 36th minute lead when Arbroath defender Stewart Malcolm's attempted clearance diverted off the backside of Alex Keddie and past Scott Morrison.
The Hoops upped the tempo in the second half and Morrison made superb saves to deny Miku and Lassad Nouioui before Arbroath shocked the home support with an 87th minute equaliser as a Steven Doris free-kick took a wicked deflection on its way into the net.
It continues Celtic's poor run at home, where they are without a win in three matches, and will cause the manager concern ahead of Wednesday's match against Spartak when they will attempt to book their place in the last 16 of the Champions League.
Lennon said his side had more than enough chances to easily win the game. "That's football. We missed far too many chances for my liking at home but we're still in the competition so we move on," the Celtic boss said. "I learned some things about some players and I'm disappointed with some performances but we had all the play and all the chances."
Paul Sheerin, who was part of the Inverness Caledonian Thistle side that grabbed a famous Scottish Cup win at Celtic Park in 2000, was full of praise for his part-time players. "To come as a part-time club, who train four hours a week, to the Scottish champions and get a result is up there with the best from a personal point of view," the Arbroath manager said.
"We were dominated and my keeper was outstanding but I asked them to stay disciplined for as long as possible and I knew there would be a chance somewhere along the line and to get a result in any manner is incredible."
Ibrahim Rabiu was handed his first start and tried his luck in the seventh minute with a shot from just outside the box that just dipped over the bar. Dylan McGeouch dragged a shot wide before captain Scott Brown drilled a shot straight at Morrison.
Arbroath were coping well with whatever Celtic were throwing at them but fell behind in the 36th minute through a comical own goal. Arbroath defender Malcolm tried to clear the ball from the by-line but blasted his attempt off the backside of Keddie, which diverted it into the bottom left-hand corner of Morrison's net.
The keeper had been helpless for the opener but came to Arbroath's rescue a minute later when he made a point-blank save to deny Brown. Arbroath tried to bounce back before the break and after a good run Mark Baxter sent in a low drive which stand-in keeper Lukasz Zaluska got down well to save.
Celtic started the second half at a higher tempo and Ibrahim curled an effort just wide from 12 yards after being picked out by Adam Matthews and Victor Wanyama then let fly with an effort that skimmed the crossbar.
Celtic came close to a second in the 68th minute when Miku smacked the post with a close range effort before Morrison made a superb save to deny the Venezuelan's shot after he connected with a Tony Watt cross.
A goal looked to be enough for Celtic before Arbroath grabbed a shock equaliser in the 87th minute when Doris drilled in a low free-kick from 20 yards that took a wicked deflection to leave keeper Zaluska with no chance.
Substitute Lassad almost conjured up a winner for the hosts in stoppage time though when he juggled the ball in the box before sending a fierce strike towards goal that Morrison superbly turned on to the crossbar.
Elsewhere, Inverness Caledonian Thistle scored a goal deep into injury time to secure a replay as the highland derby against Ross County ended in a 3-3 draw and Aberdeen scored a late equaliser to earn a 1-1 draw with Motherwell. Hibernian host holders Hearts in the Edinburgh derby.