Celtic's march towards the Scottish Premiership title was interrupted as bottom of the table St Johnstone earned a shock 1-0 win against the leaders on Sunday.
Brendan Rodgers' side were rocked b Daniels Balodis early opener at McDiamid Park and found it impossible to haul themselves back into the game.
It was St Johnstone's first win over Celtic since 2016, lifting them five points behind second-bottom Dundee in the battle to avoid relegation.
Champions-elect Celtic remain 13 points ahead of second-placed Rangers after suffering only their fourth defeat in 32 league games.
St Johnstone had lost 6-0 at home to Celtic in September and 4-0 at Parkhead in December.
But they avenged those losses in unexpected style thanks to Balodis's fourth minute strike.
Balodis headed just over the crossbar from a Makenzie Kirk cross in St Johnstone's first attack, but the Latvian defender was more accurate from Graham Carey's free-kick, glancing a header past Hoops goalkeeper Viljami Sinisalo.
A slack back pass from St Johnstone defender Sam Curtis was intercepted by Daizen Maeda, but Andy Fisher made the save to give the hosts ahead.
Five minutes before half-time, Sinisalo saved Adama Sidibeh's header from a Carey corner.
Yang Hyun-jun and Greg Taylor replaced Kuhn and Jeffrey Schlupp for the start of the second half but there was no instant improvement from Celtic.
Sidibeh did well to escape the attention of Celtic defender Cameron Carter-Vickers, only to drag his shot wide.
Reo Hatate crashed a shot against a post as Celtic tried to avoid an embarrassing defeat.
But Hatate drove high over the bar from 12 yards after being set up by Jota before Luke McCowan lashed wide from 16 yards.
James Forrest was denied by Fisher from close-range and then from distance as St Johnstone kept their survival hopes alive.