Forward Alexis Sanchez will leave Arsenal in January if a suitable offer arrives and a replacement is secured.
It is understood the Gunners hierarchy have privately accepted for some weeks that Sanchez is likely to depart after three and a half years at the club.
However, Arsenal are reluctant to sell without replacing the Chilean and their first choice is Bordeaux's 20-year-old Brazilian forward Malcom.
Manchester City is 29-year-old Sanchez's most probable destination.
Conversations have been held between the clubs but there is as yet no agreement on a fee.
Arsenal are thought to have asked for up to £35m, with Premier League leaders City initially suggesting they would pay around £20m. Sources anticipate a compromise of between £25m and £30m.
It is also widely reported that Manchester United will rival City's interest and have already made a bid.
If a deal cannot be agreed, Sanchez will be able to leave when his contract expires in the summer - a situation Arsenal are keen to avoid as they would receive nothing.
The Chile international almost joined City for about £60m on the final day of the summer transfer window, only for the switch to collapse when Arsenal failed to sign Monaco and France midfielder Thomas Lemar.
July 2014 - joins Arsenal for £35m from Barcelona on a four-year deal, despite interest from Liverpool and Juventus
May 2015 - finishes the season as Arsenal's top scorer with 25 goals, including a goal in the FA Cup final win over Aston Villa
May 2016 - finishes season with 17 goals, despite missing over a month with a hamstring injury, but the Gunners fail to win a trophy
May 2017 - top scores for Arsenal again, with 30, as they win the FA Cup but fail to qualify for the Champions League
August 2017 - agrees a £55m move to Manchester City, but Arsenal cancel the deal when they fail to sign Thomas Lemar to replace him
January 2018 - after the forward scores eight goals in the first half of the season, City again consider signing him with six months left on his deal