Right-back: Joao Cancelo (Manchester City)
This was a three-way tussle between Aaron Wan-Bissaka, Kyle Walker and Joao Cancelo for this spot. But the Portuguese gets the nod, as he is currently enjoying the best form of his career.
After struggled in his first season at Manchester City after arriving from Juventus, Cancelo has found his feet this season, streaking ahead of Walker in Guardiola's pecking order.
Centre-back: John Stones (Manchester City)
His career threatened to go off the rails in the last two years so much that John Stones didn't appear to have a future at Manchester City. But Aymeric Laporte's injury gave Stones a chance to impress, and the player has grabbed the opportunity with both hands.
It's no coincidence that Manchester City have managed to keep a clean sheet in 12 of the 16 games Stones has started this season. The player has scored thrice already.
Centre-back: Ruben Dias (Manchester City)
What a signing Ruben Dias has turned out to be! Dias has wasted no time in asserting himself as an elite defender at Manchester City, laying the most passes (2046) by any player in the division while completing 93.4% of them.
A first-choice centre-back under Guardiola, the Portuguese star has forged a solid partnership with Stones and could seriously test the mettle of the Manchester United frontline.
Left-back: Luke Shaw (Manchester United)
Manchester United's only representative in this hypothetical back four, Luke Shaw has been at the club for seven years after joining from Southampton. But it is only now he is consistently delivering the goods.
The 25-year old has been excellent at both ends of the pitch, keeping the likes of Alex Telles and Brandon Williams on the bench. Shaw has tallied five top-flight assists to his credits this campaign too.