Manchester City have opened discussions with Everton over signing England defender John Stones, according to reports.
City are currently in China on their pre-season tour but continue to be linked with a series of big-money transfers, with the Toffees centre-half said to be top of their list.
Should the move go ahead, with a £50m figure mooted, Barnsley, where Stones began his senior career, will be due a significant cash sum, through a sell-on clause drawn up when moving to Goodison Park.
Leonardo Bonucci, Leroy Sane, Gabriel Jesus and Marlos Moreno were all said to be City targets on Wednesday, but various reports suggested they are closer to bringing in Stones.
Stones, 22, has previously been coveted by Chelsea but new City boss Pep Guardiola is giving close attention to his back four given Vincent Kompany's injury record and uncertainty over Eliaquim Mangala's future.
Everton were unavailable for a response when contacted on Wednesday night, though Guardiola had talked about his defence at a press conference in Shenzhen earlier in the day.
While Stones was not mentioned by name, Guardiola described his preferred centre-half as one who could bring the ball out from the back before making a transparent reference to the transfer window.
"We need to create good build-up play, with easy passes in midfield, to achieve good passes for our strikers further up the pitch," he said.
"I believe when the ball goes from a central defender to a striker, the ball comes back as quickly as it goes, and we have to make it clear that we are building up in our first process, whether that is defenders or midfielders.
"That is why we need players of quality, to play in that style, and we have the players to do that.
"By August 31, we will have the right players to play the way we want."
The former Barcelona boss has been known to use midfielders in the back four, most successfully converting Javier Mascherano, but his suggestion that the likes of Fernando or Fernandinho could be utilised in a similar way could just as easily be seen as a veiled plea for reinforcements.
"Fernandinho can play in 10 different positions because he has the quality to play wherever," he said.
"He is quick, aggressive, intelligent and strong in the air.
"He has the quality to create good build-up play and can play a forward pass, so I think he has the quality to play there (at centre-half).
"Fernando can also play there, but maybe he is not as quick as Fernandinho. So at the end of the window, we will have to see which players we have."