Unless the 31-year-old Irishman can clear his name, he is likely to be hit with a lengthy ban plus a huge fine.

Former United player Eamon Dunphy was an earlier visitor to Bolton’s ground after being called as a witness to speak on Keane’s behalf.

Dunphy was the ghost writer for Keane’s recently released autobiography, the contents of which landed the former Ireland captain in trouble.

The FA have charged Keane with making an "improperly motivated" tackle on Manchester City’s Alfie Haaland and with profiting from the tackle through his book.

In his book, Keane indicated the tackle – since which Haaland has not played a full game – was an act of revenge for Haaland accusing him of feigning injury three years earlier when he had actually ruptured his cruciate knee ligament.

It is believed one of the key components to Keane’s defence will be that Dunphy incorrectly paraphrased his words.

It is also likely Keane will argue he has already been punished for the offence by virtue of the three-match ban he incurred for his dismissal against City.

The case will be heard by the FA’s three most experienced members of their disciplinary panel, consisting of chairman Barry Bright, vice-chairman Colin Taylor and Maurice Armstrong.

Jim Sturman QC will act on behalf of the FA while Keane will be represented by Thomas Shields QC.

Haaland will not be present at the hearing after the FA decided to use Keane’s book and a video presentation of the tackle as their full evidence.

With a welter of evidence to sift through, there is a clear possibility the case could run into a second day, although both parties were hoping for a speedy resolution.

It was confirmed that the hearing would start at 12.15pm.