Rory McIlroy sank a birdie putt from just inside 20 feet at the 18th hole to complete a five-under-par 65 first round and match Patrick Cantlay for the lead at the US Open on Thursday.Cantlay, seeking his first major triumph, and McIlroy matched the low US Open rounds at Pinehurst, two 65s by Martin Kaymer on his way to victory in 2014.