Arsenal's premier league title bid was given a significant boost without Arsene Wenger's men kicking a ball on Saturday as second-placed Chelsea were held to a 0-0 home draw by mid-table Middlesbrough.
Chelsea, seven points behind Arsenal after the Londoners' 4-2 win over Liverpool on Friday, could only close that gap by one point after well organised Middlesbrough comfortably contained them in a disappointing game.
The Blues, who ousted Arsenal in the Champions League quarter-finals in the week, have only six games left but Arsene Wenger's side can go further clear if they beat Newcastle United on Sunday at St James' Park.
Manchester United, in third, looked in even more trouble at Birmingham City after going behind to a first-half goal when keeper Roy Carroll fumbled Martin Grainger's free kick into the net.
But United levelled on the hour when Birmingham's offside claims against Louis Saha were brushed aside by referee Dermot Gallagher before substitute Cristiano Ronaldo headed perfectly inside the post.
They then clinched all three points with another header from Saha after 78 minutes to move 12 points behind Arsenal.
Elsewhere, bottom club Wolverhampton Wanderers squandered a second-half penalty by Colin Cameron and drew 3-3 in a thriller at fellow strugglers Manchester City after going two-up in the first half.
Shaun Wright-Phillips scored deep into injury time to snatch a point for City.
Leeds won 2-1 at Blackburn Rovers thanks to a second-minute Stephen Caldwell goal and a late Mark Viduka strike to move level on 31 points with their opponents.
They remain third from bottom, however, behind Blackburn and Portsmouth, also on 31 points, on goal difference. Portsmouth pinned back Charlton at the Valley in a 1-1 draw.
Leeds did, however, leapfrog Leicester City who lost 2-0 at home to Fulham with substitute Collins John scoring twice.