Kevin Thomson's neat finish on the stroke of half-time was enough to secure Rangers a 1-0 Old Firm win over Celtic and a six-point cushion at the top of the Clydesdale Bank Premier League.
Thomson finished from a narrow angle after a one-two with Jean-Claude Darcheville on the edge of the Celtic box
Scott Brown had earlier seen his close-range shot smothered by Allan McGregor, while Andreas Hinkel went closest for Celtic after the break with a long-range strike.
Eight players were booked in another hot-tempered derby affair, and Rangers are now red-hot favourites to reclaim the SPL title.
Gretna's relegation was confirmed after the crisis-hit club lost 2-0 to St Mirren at Love Street.
Craig Dargo and Billy Mehmet scored for the home side as Gretna, whose administrators made 22 players redundant in midweek, avoided a humiliating result.
David Clarkson's second-minute strike gave Motherwell a 1-0 victory over Hibernian and restored the Fir Park side to third place in the table.
Substitute Clayton Donaldson had Hibs' best effort 10 minutes from time, but was denied by a superb block by home goalkeeper Graeme Smith.
Hearts midfielder Laryea Kingston put a dent into nine-men Dundee United's UEFA Cup dream and resurrected his own side's top-six hopes with a first-half winner in a 1-0 success.
The Ghana international lit up a dull period by showing great composure to beat Lukasz Zaluska at his near post in the 27th minute.
Noel Hunt missed a great chance to equalise before the break, while Hearts winger Saulius Mikoliunas blasted over in the 59th minute with the goal gaping.
United finished the game with nine men when Garry Kenneth and substitute Danny Swanson were both given their marching orders at the death.
John Hughes saw his Falkirk side draw a blank for the second weekend in a row as they were held to a 0-0 draw by Kilmarnock.
The Bairns boss was satisfied with last week's scoreless encounter at Hearts but this result leaves them clinging to the final top-six place as the split approaches.
Their best chance fell early in the game to striker Carl Finnigan but Alan Combe saved.
Substitute Chris Maguire scored four minutes into injury-time to hand Aberdeen an amazing 4-3 success over 10-man Inverness.
Sone Aluko broke the deadlock early on, before Dave Bus scored an own goal and Russell Duncan's 25-yard-drive gave Inverness the lead.
Barry Nicholson equalised in the 45th minute and then Russell Duncan was sent off during the half-time break.
Second-half goals from Lee Miller and Roy McBain meant a 3-3 draw looked likely, only for Maguire to head in at the death to hand the Dons a dramatic victory.
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