Jesse Ryder offered a 'thumbs up' gesture and interacted with his family and manager on the day two men were arrested and charged with assault in connection with the attack that left the New Zealand cricketer in an induced coma in a Christchurch hospital.

The two men, aged 20 and 37, are set to appear in the Christchurch District Court on April 4.

Progress in the police investigation was accompanied by signs of improvement in Ryder's condition, which is now deemed stable rather than critical by medical staff. Heath Mills, the New Zealand players association chief executive, delivered a statement on behalf of the family.

"Jesse is in a stable condition in intensive care. He's been responsive and interacting with his family and the medical team," Mills said. "Jesse is still in an induced coma, and is still needing support with breathing due to an injury to his lungs. In terms of a head injury, it cannot be fully determined at this stage what the effects of a knock to Jesse's head are. We will know more once he comes out of the coma."

Ryder's manager, Aaron Klee, said the thumbs up had been delivered to a neurosurgeon at the hospital before his family interacted further. Ryder's level of sedation had been adjusted to allow him to interact with his family, Klee said, though he added that "it's awful, he's lying there with tubes everywhere".

"I was there this morning and they're working on the level of sedation of the coma to a level where they can talk to Jesse and make him aware of talking to him," Klee said. "We got a thumbs up from him this morning. Everyone was very pleased [to hear that].

"We then had some interaction with me and Jesse and Jesse's mum and Jesse's partner. We were able to talk to him and he looked at us."

Medical staff are now assessing when may be the right time to bring Ryder out of the coma. Klee expressed thanks for all the many messages of support that have come in from around the world, and said these messages had been relayed to Ryder in hospital.

Detective Senior Sergeant Bryan Archer of Christchurch police said they were now confident that only two men had been involved in the attacks.

"I've been able to review the CCTV footage and I think we can describe it as being an altercation outside Aikmans and a second incident in the carpark to McDonald's," he told reporters.

"A member of the public got involved to try and break up the fight and that's probably swelled the numbers from what people saw, but I believe the altercation involved two people initially and one person in the second incident."

A candlelight vigil for Ryder will be held outside Christchurch Hospital at 7pm local time. It will be led by the Canterbury Cricket chief executive Lee Germon and the city councillor Aaron Keown.

"I am really upset this has happened in our city and it is a really bad image for Christchurch," Keown said. "Good Friday is meant to be a day of peace and the whole country will be looking at Christchurch and saying, 'If a cricket player can't go out with his mates and not be assaulted then what is going on?'"

Ryder had been celebrating the end of the season with several Wellington team mates at Aikmans Bar in Merivale. Archer said he got into a brief altercation with a group of people as he left the bar. He crossed the road to join his team mates in McDonalds, but was assaulted before he got there.