Tottenham made it five successive league wins with a 2-0 victory at lowly Norwich thanks to second-half strikes by Robbie Keane and Michael Brown.
But erratic Newcastle twice threw away the lead at struggling Blackburn and came away from Ewood Park with just a point from a 2-2 tie.
Fifth-place Middlesbrough slipped further out of contention after losing 2-0 at rejuvenated Birmingham, with Clinton Morrison and Emile Heskey scoring for Steve Bruce's men at St. Andrews.
Stilian Petrov scored one goal and set up the other on Sunday as Celtic regained its four-point lead over traditional rival Rangers in the Scottish title race after a 2-0 victory at Hearts.
The game at Tynecastle was played a day ahead of the rest of the Premier League program and Rangers will cut the lead to one point by beating Motherwell at Ibrox Park on Monday. Teenage forward Aiden McGeady fired the Hoops ahead in the ninth minute when Petrov raced down the left wing and found him with a low cross.
Petrov netted the second goal in the 68th when Chris Sutton headed down a long-range free kick and the Bulgarian hammered the ball home with a rising shot.
"We couldn't finish the game off until Stilian Petrov scored a wonder goal but, by that time, we should probably have been out of sight," Celtic manager Martin O'Neill said.
The result gives O'Neill's men 50 points from 20 games and Alex McLeish's Rangers have 46 from 19. Third-place Aberdeen, which hosts Inverness on Monday, is 16 points behind Celtic.
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