Midfielder Richie Wellens was a trainee at Manchester United
The Football Association is investigating allegations that Swansea defender Angel Rangel threw a punch in Saturday's 3-1 win over Doncaster.
It is the second alleged incident to be looked into after Doncaster's Richie Wellens was accused of spitting on Swansea midfielder Leon Britton.
Britton accused Wellens of acting "cowardly" after the alleged incident.
Doncaster boss Sean O'Driscoll claimed he saw Rangel taking aim for Wellens during the same incident.
He said after the game: "You've got their right-back almost throwing a punch at Richie. Does he have to be sent off? I don't know.
The FA have confirmed their compliance unit have launched an inquiry into the incidents before half-time.
The alleged incidents were said to have happened while Rovers' James Coppinger was being treated for concussion.
A Swansea spokesman confirmed a complaint had been made over Rangel and the club have sent a copy of the match DVD to the FA.
Britton said of the alleged spitting incident: "It's the first time it has happened to me and hopefully the last because it's a disgusting thing.
"I would rather him have punched me than spit in my face, it's a bit of a cowardly thing to do."
But Wellens said: "I did not spit in his face but I was clearing my throat and did not aim anything his way."
Swans star Britton admitted the pair had an exchange of words before the alleged incident but said that was "normal" in football.
"We were standing next to each other and he had a bit of a problem because he thought I stamped on him," Britton said.
"I said that I didn't mean to if I did and then he started telling me he was going to punch me and all that kind of stuff.
It wasn't a face-to-face spit. I was literally by the side of him and he spat out of the side of his mouth. Maybe he was trying to provoke a reaction
Swansea City midfielder Leon Britton
"That's normal when players are unhappy with challenges. We have a go at each other and it goes on in every game.
"It's only words and nothing normally ever comes of situations like that, but the situation with Richie Wellens was a poor one from him. He spat in my face."
The FA confirmed the alleged incidents were not caught on camera or spotted by referee Scott Mathieson so the investigation will take longer than the FA's 48-hour 'Fasttrack' procedure.
The FA's compliance unit will talk to both Britton and Wellens as well as seek the observations of the other players and members of the coaching staff that claim they witnessed the incident.
"No-one, including their manager, can say they saw me spit in his face," Wellens told Doncaster's official club website."
Britton, though, added: "It wasn't a face-to-face spit. I was literally by the side of him and he spat out of the side of his mouth.
"Maybe he was trying to provoke a reaction... but you've got to rise above that."
Swansea boss Roberto Martinez immediately called on The FA to take action over former Manchester United trainee Wellens.
"There was one incident which you don't want to see on football pitches," said Martinez. "That's unacceptable.
"You get sent off for football situations but when you step over the line, I think the authorities should look at that situation."
Doncaster refused to put midfielder Wellens up for interview to respond to the allegations immediately after the game but boss Sean O'Driscoll said: "If you ask Richie, he will say he didn't do anything.
"It's something that hopefully won't make the headlines because Swansea deserved, on their performance, to win the game and they did it in the right way as well.
Wellens was sent off in the 85th minute after receiving two yellow cards in incidents unrelated to Britton's allegation.
Bookmark with:
What are these?