Chelsea allegedly find themselves at the centre of an embarrassing rules mix-up ahead of Tuesday's EFL Cup third-round tie against Lincoln City.
The Blues make the trip to Sincil Bank having suffered consecutive defeats to Bayern Munich and Manchester United respectively.
Enzo Maresca is expected to take the opportunity to make mass alterations to his starting lineup given the club's exhausting efforts at the Club World Cup during the summer.
With Joao Pedro having accumulated a lot of minutes since the semi-final of that competition, a change could be made in attack, and Chelsea would have ideally wanted to use Marc Guiu.
The Spaniard represented Sunderland in the second round against Huddersfield Town during his brief loan spell at the Stadium of Light.
Chelsea fail to notice EFL Cup rule change
In the past, that would have ruled that Guiu was ineligible for the remainder of the competition, preventing him from picking up experience in the Blues frontline.
However, as reported by BBC Sport, Guiu is, in fact, eligible to face Lincoln due to a rule change that would brought in for this season.
The EFL Cup rule in question rules that Sunderland act as Guiu's parent club for this competition as he represented them first.
As per Rule 6.4, any player that 'has appeared for his parent club in the competition prior to the closure of the summer transfer window and subsequently moved to a different club prior to the end of that transfer window' can represent a second club.
Nevertheless, as a result of Chelsea allegedly only becoming aware of this rule in the hours before the game at Lincoln, Guiu is not expected to be named in the squad.
Tyrique George is in line to start down the centre of the attack unless 17-year-old Shim Mheuka is rewarded for his form in the Under-21s with a spot in the team.
Since his return from Sunderland, Guiu has not been used for a single minute by Maresca.