The tweet was quickly deleted after it was reported to the EFL and Twitter.
The Sky Bet Championship club condemned the abuse but thanked both the English Football League and Twitter for their swift action which saw the post quickly deleted.
It is the latest instance of a Swansea player being subjected to racism, with Yan Dhanda, Ben Cabango and Jamal Lowe some of those to be targeted in the first half of 2021, while at the end of last season it was revealed Morgan Whittaker had also been racially abused online like his fellow team-mates.
“Swansea City is aware of an alleged racist tweet in response to a post on our social media channels following last night’s Carabao Cup win over Plymouth Argyle,” an official club statement read.
“We have reported the tweet to Twitter and the EFL As a result, the account has been suspended while the tweet has been deleted. We thank both organisations for the swift action taken to address this issue.
“The player targeted by the poster has been informed, while he continues to receive our unwavering support. However, we remain hugely concerned by the fact that racist posts continue to be aired on social media platforms.
“Once again, we reiterate our own strong stance on this matter, and condemn racism and abuse of all kinds because it has no place within football and wider society.”
Opponents Plymouth also released a statement condemning the behaviour of “an individual claiming to support Argyle”.
It read: “The club has been made aware of an alleged racist tweet sent from an individual claiming to support Argyle following last night’s Carabao Cup fixture at the Swansea.com Stadium.
“We condemn this behaviour in the strongest possible terms, and underline our commitment to eradicating discrimination of all forms. There is no place for it at Home Park, in football, or society.
“The club will work with the relevant authorities to ensure that the individual is identified, and appropriate action is taken.”
Swansea won the game 4-0, with Whittaker scoring a hat-trick and Dan Williams also on target.