Rust is already affecting Eden Park's redeveloped South Stand just four years after it was built - but stadium bosses have described the problem as "minor".
Opened in October 2011 as the centrepiece of the stadium's $256 million redevelopment for the 2011 Rugby World Cup, the stand is just months away from hosting thousands of fans during the 2015 Cricket World Cup.
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On Thursday abseiling maintenance workers were using grinders on the metal supports for the sound barrier that wraps around the southern stand. A worker said the team was treating rust spots.
Eden Park chief executive David Kennedy said that the work, which was being carried out by the stadium's builders Fletcher Construction, was "normal stadium maintenance" to "remove a small amount of cosmetic rust on some steel brackets".