Rob Hughes, 31, of Croydon, south London, has no memory of the assault in Crete in June 2008, but an eyewitness identified Joseph Bruckland, 22.
Mr Bruckland, from Hookwood in Surrey, and five other British men deny charges of grievous bodily harm.
Mr Hughes suffered severe memory loss and did not remember his family.
He was left with brain damage after being beaten and left for dead outside a nightclub in Malia.
Neil Philippart, who was called as a witness by the prosecution, told the court he saw Mr Hughes being hit with a bottle and fall to the ground.
Mr Philippart was asked by the judge to identify which of the defendants struck that blow.
He turned round, looked at Mr Bruckland and said it was him. Mr Bruckland shook his head when the allegation was made. He will be called to give evidence later.
The other defendants are Curtis Taylor, Daniel Bell and Sean Branton, of Horley; Surrey; Benjamin Herdman, of Worth, West Sussex; and George Hollands, of Reigate, Surrey.
The trial in Heraklion, Crete, continues.

David Obaze, 25, was fined A$3,000 (£1,643) after pleading guilty to fixing three semi-professional games in the Victoria Premier League.
Obaze is one of four Britons, all of whom played for VPL side Southern Stars, charged with corruption.
The four were handed life bans by world governing body Fifa last year.
Defender Reiss Noel and goalkeeper Joe Woolley were convicted and fined in December for throwing games.
A fourth Briton, Nicholas McKoy, 24, has also entered a guilty plea and is scheduled for a hearing in September.
One of six men accused of beating a former Oxford United footballer into a coma has been identified in court in Greece as the main offender.
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A third British footballer has been convicted by an Australian court of helping fix matches for a global betting syndicate.