Pep Guardiola's tempestuous relationship with Yaya Toure appears to have taken another twist ahead of Manchester City's Champions League opener at Feyenoord.
Toure was left out of City's squad for the trip to Rotterdam and, although he refused to be draw on specifics, Guardiola told a pre-match news conference the experienced midfielder "knows the reason why".
Guardiola coached Toure at Barcelona, where the former Ivory Coast international lost his place in the first XI and was transferred to City in 2010.
Their reunion in Manchester got off to a rocky start as Toure returned to pre-season training overweight and was then banished from the first-team picture after his agent Dimitri Seluk criticised Guardiola.
That feud was patched up in time for the 34-year-old to score both goals in a 2-1 win at Crystal Palace last November and he proceeded to play an integral part in City's season.
But Toure is yet to feature this time around and Fabian Delph and academy prospect Phil Foden were selected ahead of him as midfield substitutes for Saturday's 5-0 victory over Liverpool
"I spoke with him and he knows the reason why but it is between him and me," Guardiola said when asked about Toure's absence at De Kuip, although he clarified application in training was not the issue.
"No, no - it is just a sporting decision," he added.
"Yaya was so important last season. Six players finished their contracts last season and Yaya is the only player who we decided could stay because he is a special player.
"Hopefully [he will play again soon], it depends on him."
One player who could make an unexpected return to action is Ederson.
The City goalkeeper left the field on a stretcher at the weekend after being caught in the face by a high boot from Sadio Mane, a challenge that saw the Liverpool forward sent off.
Ederson resumed training with his team-mates wearing protective headwear due to facial scarring from the incident and was part of City's travelling party on Tuesday.
"He's got on with it straight away," said City defender John Stones, speaking alongside Guardiola.
"After the game he was speaking to the boys as if nothing happened. Shows his character.
"He just wants to be around the team and be in that environment. His face - everyone has seen the stitches and swelling.
"He's got on with it and put a scrum cap on and been in training."
Captain Vincent Kompany will miss out for City once more due to his latest calf injury setback.
"Vincent is in Manchester. He is much better. He is coming back soon," Guardiola added. "We will see in the next weeks but I think it will be soon when he comes back and fights to play."