Rowan Vine's first goal for St Johnstone gave the home side a shock 2-1 win over Celtic at McDiarmid Park.
Kris Commons drove the champions into the lead in the third minute, but Celtic were well off the pace through the vast majorty of the game.
Saints striker Gregory Tade levelled in the 18th minute before the visitors were denied what looked a clear penalty when Steven Anderson challenged Commons inside the box. In the 80th minute, Celtic paid dearly when former QPR striker Vine curled the ball in from the edge of the penalty area to hand the Perth club their first win of the league campaign.
A Michael Higdon double helped Motherwell come from behind to defeat Dundee 2-1 and remain top of the table.
Colin Nish had opened his Dundee account with a fine header after 20 minutes, but Higdon equalised from close range after 74 minutes before heading home the winner ten minutes later to deny the Dens Park side a first home win of the season.
The result preserves The Steelmen's unbeaten start to the season but was harsh on a Dundee side that had defended bravely for the majority of the match and are now at the foot of the table.
Leigh Griffiths was on target as Hibernian stretched their unbeaten league run to five matches with a 2-1 victory over Kilmarnock.
An inswinging Griffiths corner ricocheted in off Kilmarnock goalkeeper Kyle Letheren and defender Rory McKeown as Hibs took a 14th-minute lead before Danny Racchi tucked in an equaliser after 32 minutes.
Griffiths converted a 45th-minute penalty that proved decisive as Hibs claimed their second win at Easter Road this season, just one behind their tally of home SPL wins in the whole of the last campaign.
St Mirren moved into third place as Jim Goodwin's stunning strike set them on their way to a 2-0 win against Hearts.
Goodwin fired a superb 35-yard effort beyond Jamie McDonald seven minutes before half-time to give the hosts the lead, and Lewis Guy doubled their advantage three minutes after the interval as a lightning fast counter-attack ended with Steven Thompson cutting the ball back for the striker to blast into the net.
The visitors pushed men forward in an effort to find a way back into the game, but they struggled to test Craig Samson in the St Mirren goal.
Aberdeen substitute Cammy Smith's late header denied Inverness their first win of the season in a 1-1 draw that saw both sides finish with ten men.
The 17-year-old's first senior goal with six minutes to go cancelled out Richie Foran's penalty, which gave the hosts the lead mid-way through the second half.
Inverness's Owain Tudur Jones was dismissed in the 53rd minute and Aberdeen captain Russell Anderson was given his marching orders 13 minutes later, both for dangerous challenges.