The teenager, who can not be named because of his age, had previously denied a charge of attempted murder.
During a hearing at Lincoln Crown Court, the youth pleaded guilty to wounding a 19-year-old man with intent to cause him grievous bodily harm.
The incident took place at a property in Bradley Close, Louth, on Saturday May 28 this year. Lincolnshire Police said the victim suffered a head injury.
Andrew Scott, prosecuting, said the Crown Prosecution Service had reviewed the case and a plea to wounding with intent was acceptable for “justice to be met.”
Mr Scott said the victim of the attack required eight stitches to a wound and was in court with his parents to watch the proceedings.
Alison Summers, mitigating, asked for sentence to be adjourned for a probation report on the teenager.
Judge Michael Heath adjourned sentence until December 5 and remanded the teenager in to custody.