Hull may appeal against striker Adama Diomande's charge of violent conduct before Saturday's Premier League game at Watford.
Norway international Diomande is alleged to have struck Bristol City midfielder Marlon Pack in the closing stages of Tuesday's EFL Cup win at Ashton Gate and faces a three-game ban if found guilty.
"We're looking at that situation at the moment," Phelan said. "That came to our attention (on Thursday) and we looked at all the evidence that's been supplied to us, so we're going to review that.
"We'll talk to the player and see what the possibilities are of appealing or not appealing and we have to do that by the end of the day."
The loss of Diomande to suspension would be another untimely blow for Phelan, whose side have lost two successive league games since he was appointed permanent manager.
The Tigers slipped into the bottom three after a fifth straight league defeat against Stoke last week, while striker Dieumerci Mbokani is still struggling with a hamstring injury and leading goalscorer Robert Snodgrass is sidelined due to an ankle injury.
Phelan said he had been unaware of the incident involving Diomande in Bristol.
"I didn't see it at the time because it was literally just as the referee blew the whistle so I only found out (on Thursday)," he said.
"Nothing was said about it. Nothing was brought to my attention after the game.
"What I do know is that during the game there was an incident where Dio took a knock in the nether regions and he felt that quite painfully.
"But nothing was done or said about that so it's just one of those things where people have brought this to the attention of the regulative body and it's come to us now to appeal or not to appeal.
"We shall see."
Phelan, joined in the dug-out by new assistant Neil McDonald in midweek, confirmed academy manager Tony Pennock had been promoted to the first-team coaching staff and that he hoped to further strengthen his backroom team.
He said plans were already being put in place for the January transfer window but, contrary to reports, former West Ham striker Ravel Morrison, currently in Italy with Lazio, was not currently a player he was targeting.
"I haven't heard that other than what you've just told me," Phelan said. "I know Ravel, I've worked with Ravel and he's a talented kid.
"He's a talented young individual but that talent didn't always come to the fore and he's playing his football abroad.
"We are starting to look now, all clubs are starting to look for January now and trying to get the preparation in place so that we don't leave it as late as we have done in the past."
Source: PA
