OAKMONT, United States (AFP) - Andrew Landry was holding onto his first round lead at the second day of the rain-hit US Open at Oakmont on Friday, but some big names were on his shoulder.

The 28-year-old Texan, ranked 624th in the world completed a first round of four-under par 66 on Friday morning.

That gave him the lead, one ahead of England's Lee Westwood and last year's runner-up Dustin Johnson, with the tournament running well behind schedule.

A shot further back came Spain's Sergio Garcia, American Scott Piercy and Shane Lowry of Ireland.

Camped on 69 were US amateur Scottie Scheffler, fellow Americans Kevin Streelman and Bubba Watson, along with New Zealander Danny Lee.

It was a tough finish for 2011 US Open winner Rory McIlroy. He bogeyed the last three holes and at 77 was 11 shots off the pace and facing a battle just to make the cut.

Defending champion Jordan Spieth had a 72 and Masters champion Danny Willett a 75.

World number one Jason Day was also in some trouble at four-over after 15 holes, but six-time runner-up Phil Mickelson was holding firm at two-over also through 15.