All Black winger Zac Guildford has voluntarily stood down from the Crusaders after a late-night incident at a home in Christchurch last weekend.
The New Zealand Rugby Union says it has launched misconduct proceedings against Guildford.
NZRU chief executive Steve Tew says his union and the Crusaders are very disappointed by the incident but declined to comment further.
Zac Guildford has been suspended from the Crusaders in the past for alcohol-fuelled off-field incidents.
In 2011, he was supended by the NZRU for four weeks after claims he punched patrons at a bar in Rarotonga while intoxicated, bleeding and naked.
However All Blacks coach Steve Hansen said last year he was happy with Guildford's off-field progress.
The coach of the Crusaders, Todd Blackadder, wouldn't elaborate on the latest incident, except to say it was serious but so far the police are not involved.
Blackadder says it could lead to Zac Guilford no longer being employed by the NZRU, and he is disappointed and saddened by what has happened.