Sunday's 4-0 mauling at the hands of Manchester United was tough to take for Chelsea fans, and probably even tougher for manager Frank Lampard, whose return to Stamford Bridge was ruined.
After the game, Lampard was quick to point out that he wasn't able to field his strongest side, given the likes of Ruben Loftus-Cheek, Callum Hudson-Odoi and Antonio Rudiger are all battling injury.
However, another youngster who was name-dropped by the boss was right-back Reece James, who is yet to play a single minute of senior football for the Blues.
It hurts to say it, but Azpilicueta is not the player he once was. The loyal Spaniard has been steadily declining for months now, and his frailties were exposed once more against United.
Caught too high up the pitch, the man known as 'Dave' simply didn't have the legs to get back and track the likes of Marcus Rashford and Anthony Martial, which isn't even a new problem. Under Maurizio Sarri, Azpilicueta was also guilty of regularly leaving his side exposed, but Davide Zappacosta was never viewed as an acceptable alternative.
Even going forward, Azpilicueta looks to have lost his creative vision, and he has been guilty of losing possession far too often for a defender who isn't capable of getting back and making up for his mistake.
Lampard's preferred tactic requires his full-backs to attack with speed and precision, and Azpilicueta doesn't offer either anymore.
Coming off the back of a stellar campaign on loan with Wigan Athletic, the 19-year-old injured his ankle this summer and hasn't been seen since. Fortunately, it looks like Lampard knows exactly what he has on his hands, which will largely be thanks to assistant Jody Morris' time with the academy.
James is an incredible blend of speed and power, but that is just the start for the teenager. Defensively, he has the agility and stamina to fly up and down the field, but also the technical ability to make an impact at both ends.
As arguably Chelsea's finest crosser, James is an incredible passer - one who creates chances out of nothing with stunning regularity. He even played in an advanced role for Wigan at times because they found themselves relying on his creativity, even when he was a right-back.
He thrives on getting the ball into the box, and rarely fails to create chances. However, if he does lose the ball, he doesn't struggle to get back. He can track even the fastest forwards and has pulled off more incredible tackles than you can imagine.
Simply put, he offers everything Azplicueta used to, and that's why Chelsea need him back to full fitness as soon as possible. He can help answer Chelsea's defensive conundrum, and he wouldn't cost a penny.