City are accused of overstating sponsorship revenue to hide that they had not complied with UEFA's financial fair play (FFP) rules between 2012 and 2016 and were also handed a 30 million euro ($34 million, £27 million) fine.
UEFA's case was prompted when German magazine Der Spiegel published a series of leaked emails in 2018 that purported to show how City manufactured extra sponsorship revenue from a series of companies with connections to the club's Abu Dhabi-based owner Sheikh Mansour.
Under the Sheikh's ownership, City's fortunes have been transformed from perennially living in the shadow of local rivals Manchester United to winning four Premier League titles in the past eight years.
However, billions of investment in players and managers has not yet been able to deliver the club's first ever Champions League title.
City are still involved in this season's competition and will be allowed to compete should the 2019/20 edition of Champions League return in August no matter the outcome of the appeal.
But a two-season ban from the competition would represent a huge blow to the club's prestige, finances and hope of hanging onto manager Pep Guardiola and key players like Kevin de Bruyne and Raheem Sterling.
"Two years would be long. One year is something I might be able to cope with," De Bruyne told Het Laatste Nieuws last month.
City banked 93 million euros from prize money and television rights alone by reaching the quarter-finals of last season's Champions League.
The added loss of gate receipts and commercial revenue would make it extremely difficult for the club to meet FFP regulations in the future without cutting costs.
City have steadfastly refuted UEFA's allegations.
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