Manchester City have made up big gaps on Manchester United before, and they produced one of their more convincing league performances of the season to let their rivals know they are not going to let go of the title easily.
Newcastle were much improved too, but only briefly in the game. Since the home defeat to West Ham last month that gave Sam Allardyce so much inner satisfaction, the Magpies have lost six of their last seven league games, the only victory in a shocking run coming against 10-man Wigan.
If the home fans were hoping that was a sign of promising things to come they were quickly disappointed. The visitors swept into the lead on 10 minutes and could have had a couple more before the mid-point of the first half. Samir Nasri, effectively called half a player by Roberto Mancini last week, was prominent in most of the City attacks and actually looked for the first time in months like the threat he used to be for Arsenal.
It was a splendid ball forward by Yaya Toure from half way that set up the opening goal, yet Nasri was onto it in a flash, just managing to stay onside, and had squared a pass to leave Sergio Aguero a tap-in before the Newcastle defence had properly woke up to the danger.
Carlos Tevez forced a point-blank save from Tim Krul moments later from a David Silva pass, then narrowly failed to reach another square pass from Nasri that was begging to be touched in at the far post, before Nasri hit the post from a tight angle a couple of yards out when he should probably have supplied the second goal.
With Tevez missing another golden opportunity from a Nasri square pass before the half hour it began to look as if City might regret not making their creativity count, especially as Nasri was forced off with a groin strain 10 minutes before the break.
It did not work out that way, even with Tevez continuing to miss chances. He managed more of a cross than a shot when Silva gave him a sight of goal in the 38th minute, but the ball touched David Santon on the way out and from the resultant corner Javi Garcia headed City into a comfortable lead.
The hapless Santon was on the line and in a position to deal with the downward header, yet made a complete hash of his attempted clearance and saw the ball bounce over the line off his standing leg.
The half-time score was a fair reflection of the first half. City had bewildered their opponents with the speed and slickness of their first time passing and could have had more. Apart from Ba's early attempt, Newcastle managed only hopeful efforts from Mike Williamson and Papiss Cisse before the interval.
Real hope arrived early in the second half when Ba pulled a goal back with an opportunist strike, after Fabricio Colocinni returned a half-cleared corner to find the City central defence had deserted the danger area in front of Hart.
Moments later the same thing happened again, neither Kolo Toure nor Matija Nastasic were in a position to close down Cisse when he received the ball from Vurnon Anita and turned to make space for a shot, but presented with a chance to alter the course of the game he fired early and over the bar.
At least the goal livened up the second half and encouraged Newcastle to play some of their best football, with Jonas Gutierrez going closest to equalising with a shot from an impossibly narrow angle. For a while the outcome hung in the balance, even after Mancini sent on Edin Dzeko to add height to the attack, but Newcastle were undone when Silva and Pablo Zabaleta fashioned some space on the left, for a cross from the latter that was steered through a crowd of players by Yaya Toure at the near post.
It was not defending of the highest quality, Newcastle appeared to be more worried about the ball reaching Dzeko or Aguero, though Toure timed his run well and his touch was decisive.