Sluggish start for Rory McIlroy at Oakmount

The four-time major winner missed the fairway on each of the first three holes

Rory McIlroy's conservative approach failed to pay dividends as he struggled to take advantage of ideal conditions for the early starters in the first round of the US Open.

More than an inch of rain fell overnight to soften the course and slow Oakmont's severely sloping greens, which were described as "legendarily fast" by USGA chief executive Mike Davis on Wednesday.