Like most managers, Jose Mourinho has rarely been one for making unnecessary changes to the heart of his defence. In fact, even amid an era in which squad rotation largely reigns supreme, the Manchester United boss usually prefers to keep his starting XI as consistent as possible - hectic fixture list allowing.

And as things stand, Eric Bailly and Phil Jones appear to be Mourinho's first-choice partnership at the back. The Ivorian and the England international began the season in the starting XI and perhaps most tellingly, both were injected back into it instantly against Tottenham Hotspur on Saturday after recovering from respective injury problems.

But slotted between Bailly and Jones in an uncharacteristic back three was a player reminding Mourinho that his centre-back selections this season shouldn't be a foregone conclusion - Chris Smalling. In a pragmatic performance that hinged on United's ability to claim a clean sheet while capitalising on rare moments at the other end, it was the 6 foot 4 centre-half who had arguably the biggest impact.

Indeed, Smalling made the most interceptions and clearances of any player on the pitch, while ranking joint-second for tackles and aerial duels won. But perhaps most impressively considering how influential the 27-year-old was at the back and how fine the margins were on Saturday, when one superb Christian Eriksen free kick could have been the difference, he did it all without committing a single foul.

Of course, things could have been different if Harry Kane was fit for the trip to Old Trafford. Tottenham didn't cause an abundance of problems until Dele Alli missed a key chance late on. But Smalling's performance was a real statement in the context of United's defensive pecking order, and inevitably begs the question of what their strongest centre-back pairing actually is.

Let us know which two defenders you see as United's best by voting below...

https://video.footballfancast.com/video-2015/PL25(12-13).mp4