Fulham are interested in signing left-back Joe Bennett from Championship rivals Cardiff City.
The 27-year-old former Aston Villa player missed Tuesday's 2-0 win over Sheffield United, which kept Cardiff top of the league, through injury.
Cardiff manager Neil Warnock confirmed after the game that Fulham had made an approach.
"I think they're [Fulham] talking to our people. I'm not aware of anything definite," he said.
"I think he has a buyout clause in his contract and then it's up to them, if they meet it then they're entitled to talk to him.
"It doesn't mean he's going anywhere but they're entitled to talk to him."
Bennett has made 26 appearances and scored three goals for the Bluebirds since signing on a free transfer from Aston Villa in the summer of 2016.
He played the opening two games of this season but a minor knock saw Bennett sit out the win over the Blades, as Cardiff won their opening three league games of a season for the first time in the club's 107-year Football League history.
Cardiff switched Jazz Richards to left-back to cover, with Bruno Ecuele Manga asked to fill in at right-back.
Warnock indicated he would rather not lose Bennett but said he was happy with his squad, although Cardiff have been linked with Wigan striker Omar Bogle and Watford midfielder Ben Watson.
"We've got a very good squad and it's nice to have options," Warnock added.
Cardiff next go to Molineux on Saturday, 19 August for a top of the table clash with a Wolverhampton Wanderers side who have also won their opening three games.
"They've had another great win [3-2 at Hull City]," Warnock said.
"The money that they've spent, it's going to be a great to go up there and test ourselves against one of the most expensive squads.
"I think the lads are looking forward to it really."