Rennes manager Julien Stephan has told M'baye Niang to reconsider his decision in wanting to join Marseille insisting all his players need to be "fully integrated in the project".
The profile of the Brittany-based club has risen in recent seasons and went a step further this year after they finished third in the abruptly-ended Ligue 1 campaign because of the coronavirus pandemic.
This gives them a path into the Champions League next season which they will start from the third qualifying round and Niang's involvement will be very crucial after he finished as Rennes' top scorer with 15 goals in all competitions.
The continuous link of the 25-year-old Senegalese to Marseille, which he has admitted he is open to, will be a hindrance to Rennes' plans.
"I don't have to judge, everyone is free to control their communication," Julien told Ouest-France.
"What I'm saying is that we need to have everyone fully integrated into the project because in Rennes if we are not collectively very good, there are other clubs who have more means than us.
"If you want to counter this difference, it necessarily involves an irreproachable state of mind and a very strong identification with the club. This will be an important criterion for continuing to develop."
Niang was recently involved in controversy after he was found to have broken lockdown rules on May 12 to see his horse “Swetty Beauty” win a race in Marseille.
He was subsequently fined €1500 and admits he was caught up in the preparations of the race.
“At the start, it was my friend Benjamin Andre, also a horse owner, who constantly talked to me about races, read the turf, analysed this or that race," Niang told Paris-Turf.
"By dint of hearing it, I got caught up in the game."
Niang's senior career began in 2011 and he has scored 62 goals and provided 31 assists in 271 appearances.
He has represented Caen, AC Milan, including loan spells at Montpellier, Genoa, Watford and Torino.
Niang's accolades include winning the 2016 Italian Supercup with Milan and the 2019 French Cup with Rennes.
He was also runner-up at the 2019 Africa Cup of Nations with Senegal.