Celtic was stunned by Hearts on Sunday, slumping to a 2-0 loss that left champion Rangers nine points ahead of Motherwell in the Scottish Premier League.
Rudi Skacel put Hearts ahead with a 58th-minute strike from the edge of the penalty area and Celtic was reduced to 10 men seven minutes later when Kris Commons was sent off for a challenge on Adrian Mrowiec.
Ryan Stevenson scored a breakaway second in the 80th to leave third-placed Celtic 10 points behind SPL leader Rangers, albeit with one game in hand.
Motherwell is second — a point ahead of Celtic — after winning 3-1 at Dundee United on Saturday when Rangers beat Hibernian 1-0.