An unemployed man has admitted to stomping on the face of an off-duty police officer with such extreme force he was knocked unconscious in the middle of a busy road.

Koby Weaver pleaded guilty to reckless grievous bodily harm in company when he faced Sydney's Downing Centre Local Court on Thursday.

A second charge of assault occasioning actual bodily harm in the company of others was subsequently withdrawn by the prosecution.

The 21-year-old was arguing loudly with his friends Danai Deneiderhavsein, 18, and Finley Goodwin, 23, on the night of January 22 on a busy street in Newtown, in Sydney's inner-west.

They were described as worked up and aggressive by off-duty police officers Jack Steen and Lachlan Gray, who caught the trio's attention just before 11pm, according to court documents

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