Champions Rangers reduced Celtic's lead in the Scottish Premier League to eight points with a 2-0 win at Dundee yesterday.
First-half goals from Nuno Capucho and Michael Ball secured victory to take Rangers to 44 points. Celtic thrashed Hibernian 6-0 at home on Saturday.
The Glasgow sides meet in the second Old Firm derby of the season next Saturday and Rangers probably have to avoid defeat to keep alive realistic hopes of retaining their title.
"There's no doubt it was a crucial win for us today before we go to Celtic Park next week," Rangers manager Alex McLeish said.
Rangers, with Australian defender Craig Moore back from injury, went ahead on six minutes when Capucho headed home a cross from Chris Burke.
Dundee had chances to level but Ball's 35th minute strike from a long-range free-kick that swirled into the net secured the three points.
Celtic's win over Hibernian was their 17th straight league win and swift revenge for Martin O'Neill's side who suffered a shock 2-1 defeat by the same opponents in a League Cup quarter-final this month.
Two goals each from Chris Sutton and John Hartson put Celtic 4-0 up after an hour before Henrik Larsson and Stilian Petrov completed the rout. Hibs were reduced to 10 men just before half-time after Derek Riordan was dismissed.
"It closes off 2003 very nicely for us and we're absolutely delighted with the run. We're scoring goals, playing very strongly at the moment and are keeping the fans happy but, of course, we must start again next week," said O'Neill.
Sutton opened the scoring after four minutes and Hibs crumbled after Riordan was red-carded for a late challenge on Jackie McNamara.
Hartson headed home the second while Sutton netted the third from the penalty spot. Hartson made it four with a fizzing low strike and Larsson got in on the act with number five after poor defending.
Petrov completed the rout with 13 minutes left to leave a 59,609 home crowd, Celtic's biggest of the season, in a buoyant mood.
Third-placed Hearts were held to a 0-0 draw at home by Motherwell. Bottom club Partick Thistle thrashed Dunfermline Athletic 4-1.
