Just days after a tough loss at Barcelona in the Champions League, Celtic lost 2-0 to Kilmarnock in the Scottish Premier League at Parkhead on Saturday.
Celtic lost 2-1 at Barcelona on Tuesday on an extra-time goal from Jordi Alba, and the hangover resulted in a second league loss and first at home. Celtic is still atop the standings, two points clear of three clubs.
Cillian Sheridan and Liam Kelly scored for Kilmarnock, which ended a two-match losing skid with the surprising win in Glasgow. Celtic had won its last four league matches.
Aberdeen joined the group of teams two points off the pace as Niall McGinn and Jonathan Hayes scored in a 2-0 win over Dundee on Saturday. Aberdeen extended its unbeaten run to 10 games, dating back to a season-opening loss at Celtic.
Promoted Dundee has lost nine of its last 10 matches, and sits at the foot of the table with just four points from 11 games.
David Robertson scored two minutes into stoppage time as St Johnstone escaped with a 1-1 draw Saturday at Inverness to extend its unbeaten streak to seven games and move to within two points of Celtic.
Inverness is unbeaten in six matches and five points off the pace.
Also Saturday, Johnny Russell scored in second half as Dundee United snapped a six-game winless run with a 1-0 win over St. Mirren, and John Sutton scored in stoppage time as Hearts tied Ross County, 2-2.