Paralympian athlete Oscar Pistorius fired a gun in an upmarket restaurant, grazing his friend's foot, and then asked another to take the blame, a South African court has heard.

It is the third day of the athlete's trial for murdering his girlfriend Reeva Steenkamp on Valentine's Day last year.

Mr Pistorius maintains he shot the 29-year-old through a locked bathroom door in the early morning hours thinking she was an intruder.

Today, the state called his friend Kevin Lerena to testify about one of three other charges against Mr Pistorius.

A bullet Mr Pistorius allegedly fired in a Johannesburg eatery, Tashas, in January 2013 grazed the 21-year-old professional boxer's foot, he testified before Judge Thokozile Masipa.

"A shot went off in the restaurant, then there was just complete silence," said Mr Lerena, the state's fourth witness in Mr Pistorius's murder trial.

"Once the shot went off, I was shocked," said Mr Lerena, who also calls himself the 'KO Kid'.

"I looked down, and just where my foot was stationary, there was a hole in the floor."

"I had a little graze on my toe. I wasn't hurt or injured," he said, but added that "there was blood".

The athlete apologised profusely, but then asked his friend Darren Fresco, the owner of the gun, to take the blame.

"Please, I don't want any attention around me. Just say it was you," he pleaded, according to Mr Lerena.

Mr Lerena said he met Mr Pistorius at a luxury car dealership.

The Daytona Group, which sells Aston Martins and McLarens, is run by another friend of Mr Pistorius, state witness Justin Divaris.

British 400-metre sprinter Martyn Rooney, one of the four friends at the restaurant, was training with Mr Pistorius at the time.

The gun allegedly went off after Mr Fresco passed it under the table to Mr Pistorius.

He is also charged with firing a gun through a moving car's sunroof and with the illegal possession of ammunition.

The state is expected to use these incidents to illustrate past reckless behaviour in their argument to prove the runner planned to kill Ms Steenkamp.

At Pretoria High Court, Mr Pistorius' defence team wound up its cross-examination of a third prosecution witness, who said he had heard shouts and screams from Mr Pistorius' house before shots were fired on the night Ms Steenkamp died.

Earlier, lead defence advocate Barry Roux tried to undermine the testimony of wife and husband Michelle Burger and Charl Johnson, who lived 177 metres away in an adjacent housing complex, as being too similar to be credible.

"You could just as well have stood together in the witness box," he said, earning his second rebuke of the three-day-old trial from Judge Thokozile Masipa.

The trial is being broadcast daily on live television, a first for South Africa, although most witnesses have asked for their faces not to be shown to protect their identity.

Mr Johnson said today he had received "intimidating" phone calls the previous night from people who had heard his phone number read out in court during his wife's earlier cross-examination.