The sight of the Manchester City players after their 2-1 Boxing Day win over Liverpool spoke volumes.

United in celebration, they knew how vital the victory was, dropping the leaders down to fourth place and moving up to second themselves.

This was as tough as it had been at the Etihad in a Premier League encounter this season. Nine wins out of nine, with 20 goals in games against Manchester United, Arsenal, Spurs and Newcastle, are impressive numbers.

But most impressive was the way Manuel Pellegrini’s men dug deep to come back from a goal down and overcome an enterprising Liverpool side that looked every inch title contenders themselves.

It is that indefatigable spirit, that iron will to win, which defines champions, and why they are backed to be crowned kings for the second time in three seasons.

While Liverpool, Arsenal, Chelsea and neighbours United will still have a say in how it all unfolds come May, Reds boss Brendan Rodgers was absolutely right when he claimed the title is City’s to lose.

There is a confidence and conviction that wasn’t quite there in the 2012 campaign. Back then, there were more nerves and tactics that often negated the opposition rather than provide a platform for their own talent to flourish.

Now there is a strut and swagger to complement an attacking style that is breathtaking to watch. Questions were rightly asked following a 1-0 loss at Sunderland in November about the mindset of the players and the new manager’s methods.

But nine successive wins and a draw at Southampton have provided the perfect response. Like the great English sides of old, be it Liverpool in their pomp, the Arsenal record-breakers or Sir Alex Ferguson’s United, there is an air of invincibility about City.

The Etihad has become a fortress and only Chelsea and Southampton are likely to threaten their historic bid to claim 19 league wins out of 19.

But, crucially, Pellegrini has also now got them firing on their travels too, with that fine win in Munich over Bayern a factor. It has taken a little time, but the ‘Engineer’ has built a powerful machine.

With the January addition of perhaps a left-back, another dominant central midfielder and striker – to ease the burden on Yaya Toure and allow time for Sergio Aguero and Stevan Jovetic’s injury troubles to heal – there will be few who can stop City.