Rangers and Celtic limbered up for Saturday's Old Firm showdown with routine victories in the Scottish Premiership. 

Rangers maintained their 16-point lead over Celtic at the top with a 2-0 win at St Mirren while the Hoops, who have three games in hand on their rivals, sank Dundee United 3-0 at Parkhead. 

Rangers were second best for much of the first half against the side who shocked them in the League Cup a fortnight ago, but they went ahead with their first shot on target after 28 minutes. 

Ianis Hagi fed Kemar Roofe, whose low drive took a deflection off Conor McCarthy as it flew past goalkeeper Jak Alnwick. 

Steven Gerrard's side doubled their advantage before half-time when Alfredo Morelos pounced on Joe Shaughnessy's under hit backpass. 

Rangers' Steven Davis is put under pressure by St Mirren's Ethan Erahon

Ismaila Soro's first goal for Celtic, a swerving 25-yard effort which deceived United keeper Benjamin Siegrist, gave them the lead after 23 minutes. 

Five minutes before the break David Turnbull made it 2-0 with a low strike from distance in off the post for his fourth goal in six games. 

Odsonne Edouard wrapped up the victory when he raced on to Leigh Griffiths' ball over the top and neatly lobbed Siegrist. 

The only downside was the sight of Hoops defender Christopher Jullien going off injured three days before the trip to Ibrox. 

Elsewhere, strugglers St Johnstone and Hamilton laboured to a goalless draw at McDiarmid Park. 

Michael O'Halloran should have won it for the hosts late on but he missed the target from close range. 

Livingston's game against Aberdeen was postponed due to a frozen pitch. 

The artificial surface at the Tony Macaroni Arena fell foul of the conditions and was called off shortly before the scheduled 4pm kick-off.