Samuel Clarke, 28, had been drinking since 10am when he hit his partner with the booze - at around midnight on January 23.
Annabel Lenton, prosecuting, told Derby Crown Court Clarke and his partner were watching TV game shows on a sofa when the random attack happened.
She said: “The defendant got up out of nowhere and threw a Prosecco bottle at her directly in the mouth with such force that it broke a tooth in half.
“She described being confused, not knowing why the defendant had done this.
“The defendant then threatened that he would tell the police that she smashed his face and hand to discourage her from reporting it.”
Ms Lenton said Clarke and his victim had been friends before getting into a relationship in July last year and he was described as suffering mental health issues and alcoholism.
Ms Lenton said the victim had no faith that a domestic violence protection order would work, as they had not worked in the past.
While the girl’s mother said in a statement that she “had not been the same since meeting the defendant”.
The court heard Clarke had eight convictions for 10 offences - including three domestic incidents with past partners.
During one he punched a woman to the chest and took her handbag, stealing £50.
Clarke, of Ashton Close, Swanwick, admitted assault with actual bodily harm.
However his sentence was adjourned to give the defendant - who was expecting to be sentenced in May - more time to seek input from mental health services and the probation service.
Recorder Michael Auty QC told him: “In all the circumstances what I need you to understand is this case is serious and any court will consider a sentence of imprisonment of some length.”
However he added: “It’s you right that we must deal with every case justly – I accept that you were expecting this case to beard on May 16."