A teenager was shopping for cannabis when he attacked a man with a hammer, a court was told.
But his childhood friend, Osa Akpata, has denied attempted murder, GBH and possessing a knife as an offensive weapon.
Akpata claims he was not with Knight when the attack happened in The Downs, Harlow, Essex, on 26 January this year.
Akpata, 20, from Bishops Stortford, Herts, said he had been with Knight earlier, but left him to go to his grandparents’ house in Harlow shortly before the assault. He told the jury that he met up with Knight later that afternoon after receiving a “worried” sounding call from him.
Mr Summerville, 24, was seen on a resident’s CCTV being chased by two men and set upon at 1.30pm. He was hit with a hammer and stabbed and suffered numerous cuts and a punctured lung.
The victim did not attend Chelmsford Crown Court. In his statement read to the jury, he said he had walked past two men, one of whom said something. One then said “get him” and he was chased.
Mr Summerville said one man was white and one was black, but he had never seen them before and didn’t know who they were.
Giving evidence in his defence, Akpata said he had known Knight since he was 12. He said that on January 26, he and Knight were in Harlow together. He had arranged to call in on his grandparents and arrived at their house at about 1.40pm.
He said they were out so he let himself in, “cleaned and tidied” the house, and that Knight rang him about 3pm.
He continued: “He said ‘something had happened’ and for me to meet him urgently. He said he didn’t want to talk about it on the phone. He sounded very worried.”
He said that when they met, Knight was alone and nervous and told him that after they had split up, he had met a man called Abdul Quifer and they rang another friend “to buy some cannabis”.
When they were with the drug contact two other males turned up, one of whom was Robert Summerville, said Akpata.
He said the three of them had then tried to rob Knight and continued: “They were armed with knives. Charlie said he pulled out a hammer he was carrying and attacked Summerville with it.
“Charlie said the other two ran off and he and Abdul chased Summerville, got him and attacked him.”
Akpata added that Knight told him “Abdul stabbed him with a screwdriver”.
Akpata denied he was “the second man” in the attack on Mr Summerville, pointing the finger instead at Abdul Quifer.
The jury has been told of Knight’s guilty pleas. He will be sentenced later.
The trial continues.