BBC Sport golf correspondent Iain Carter analyses the controversy of Rory McIlroy's "non-conforming" driver at the 107th US PGA.

Kerry Haigh, the chief officer for championships in the PGA, pointed out that the USGA does not want to get involved in whose driver is not in accordance with the rules.

Rory McIlroy declined to speak to the media for the fourth day in a row at the US PGA Championship, as he finished outside of the top 40.