Champions Celtic drew 1-1 at Motherwell yesterday after conceding a stoppage-time goal by Darren Lee Smith in their Scottish Premier League (SPL) clash.
Celtic's Derek Riordan pounced in the first half after Motherwell keeper Graeme Smith had pushed away a shot from Japanese midfielder Shunsuke Nakamura on 36 minutes and he angled in a six-metre shot from the right.
Smith rattled a close-range shot beyond keeper Artur Boruc in stoppage time, moments after Thomas Gravesen had struck the right post with a 20-metre shot.
Elsewhere, Rangers stumbled to a 1-1 draw at home to lowly St Mirren to pile more pressure on under-fire manager Paul Le Guen.
St Mirren took a first-half lead with a Richard Brittain shot from 20 metres into the bottom right, but Rangers striker Kris Boyd headed the equaliser five minutes later from a cross by Charlie Adam.
Aberdeen crashed to a 3-1 defeat at Dundee United and had Richie Hart sent off on 65 minutes for a second bookable offence.
Celtic top the SPL standings with 53 points from 22 games, while Aberdeen remain second with 37 points and Rangers third a point behind.