Neymar has not been called up for Paris Saint-Germain's Ligue 1 opening clash against Nimes on Sunday, with talks over a move to another club at an "advanced" stage.
Sky Sports News understand Real Madrid remain in talks with PSG over the signing of Neymar and sporting director Leonardo has told French media that negotiations over Neymar potentially moving to unspecified clubs are "more advanced", although no agreement has been reached.
The reigning French league champions begin the defence of their title on Sunday and PSG boss Thomas Tuchel said that Neymar was omitted from the squad to play Nimes due to a training injury.
Regarding the 27-year-old's proposed return to La Liga, Barcelona head coach Ernesto Valverde said: "As it stands, I don't know what is going to happen.
"If he leaves or not there are many things, but in principle I don't know what will happen and I'm not thinking about him (Neymar), just about tomorrow."
The Brazil forward is understood to have told PSG he wants to leave the club this summer, having joined from Barcelona in 2017, but the French champions have yet to receive a formal offer.
PSG are unlikely to sanction a sale unless they are able to recoup the £200m they spent on Neymar.
Barcelona vice-president Jordi Cardoner said a move to re-sign the 27-year-old can be "ruled out" at this time and that opens the door to a controversial switch to their arch-rivals.
The summer transfer window closes on September 2 at 23:59pm for clubs in Ligue 1 and La Liga.
Neymar enjoyed four trophy-laden years in La Liga with Barca, winning two league titles, a Champions League and FIFA Club World Cup.
He also won back-to-back Ligue 1 titles with PSG, for whom he joined for a world-record £200m fee in 2017, scoring 51 goals in 56 appearances.
Real Madrid have been busy in this transfer window after finishing 19 points behind champions Barcelona last season.
Eden Hazard, Luka Jovic, Eder Militao, Ferland Mendy and Rodrygo have all moved to the Bernabeu while Real also had a bid of £27.6m plus James Rodriguez for Paul Pogba rejected.