A man accused of murdering a teenager had been involved in a disagreement with him in the weeks before he was stabbed to death, a court has heard.
Tristan Kerr, 17, from Abertridwr, in Caerphilly, bled to death in the street minutes after being stabbed in the heart and lung with a so-called Zombie knife on 5 February.
Connor Palfrey, 25, from Abertridwr, Georgie Mears, 19, from Thornhill, Cardiff, Elexi Manny, 25 from Senghenydd, Caerphilly, and Ricardo Elliot, 27 of no fixed address, all deny murder through joint enterprise.
Joint enterprise means people who assist or encourage another person to commit a murder can be convicted for the same crime.
Kerr was attacked in the living room of a flat in Lower Francis Street in Abertridwr which was home to 31-year-old Ieuan Crane, the court heard.
Giving evidence at Newport Crown Court, Crane said Palfrey had what he described as "beef" with Kerr following an incident in which the teenager was said to have chased Palfrey with his dog.
"He [Kerr] was just chasing him," Crane said.
"At that time there was a beef. A week or two after he went to see Connor Palfrey and they squashed their beef," he said, meaning they resolved the issue.
On the day the teenager died, Crane said he, Kerr and two other men were sitting in the living room of his flat "just chilling", playing computer games and watching YouTube when Palfrey and Mears burst in through the unlocked front door.
"Tristan didn't have a chance to do anything. It happened like that," he said, clicking his fingers.
In a police video interview played to the jury, Crane said Palfrey had been armed with a block of wood that "might" have had a nail in it.
He told officers that at first, he did not realise Mears was armed with what he later described as a "big" knife with a "Zombie, Rambo blade".
"I thought he was punching him.
"I didn't see the knife until after the fourth time," he said.
Crane said he tried to grab Mears' arm and wrist, but Palfrey threatened him with the block of wood. He said he was trying to stop the attack on his friend.
Kerr and another friend known as "Custard" escaped through the back door of the flat, the court heard.
"I pushed them out of the house and locked the door, they went in the car, the car was on the drive," he said.
Crane said he only realised Kerr had been badly hurt when he went out into the street and his friend Custard told him: "It's bad."
"I didn't even know if he was hurt or nothing. I didn't see no blood as he ran out. I thought he was sound, then I saw him collapsed in the street.
"I could see blood dripping down to his socks, he had white socks. I didn't know what to do. I couldn't move him.
"A lady came out, a nurse, looking for a stab wound trying to clean it."
Crane said he had known Kerr for two years, and that the teenager came to his flat every day to see his lurcher greyhound cross dog which Crane was looking after.
He said Kerr would come to visit in the morning or afternoon but had to leave by 20:00 because he was on an electronic tag.
A large quantity of cannabis was later found in the freezer at the Lower Francis Street flat along with a shotgun cartridge and weighing scales.
In cross-examination, Crane admitted smoking cannabis, but said he had forgotten about the drugs in the freezer and did not know anything about the weighing scales or the shotgun cartridge.
He said he did not "knowingly" allow any of his friends to deal drugs from his home.
Asked by Chris Rees KC, defending Mears, if Kerr dealt drugs, Crane said he was "not sure".
"Tristan Kerr was dealing drugs from your address?" Mr Rees KC asked. "Not to my knowledge," Crane replied.
He said he knew the teenager was taking ketamine.
Crane was asked if he thought Kerr had been attacked because he was trying to "rob Georgie Mears of drugs."
He said he didn't know why Kerr had been attacked.
He told Rees KC: "I don't know why you think I'm in the know. I had no clue what this was about. I thought it was about a girl."
The four defendants were later arrested in Hereford.
The trial continues.