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

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.

Rory McIlroy had a new driver for the PGA Championship after it was reportedly ruled his previous club was non-conofirming when tested before practice at Quail Hollow earlier in the week