Poulter led by one from Ryder Cup team-mate Nicolas Colsaerts, who had birdied the 13th and 14th, South African duo Charl Schwartzel and Tim Clark - one of nine players taking legal advice about the anchored putting ban - and American Charley Hoffman.

Thunderstorms had been forecast with an 80% chance of a rain on a course already playing very soft following almost six inches of rain in the past week.

Play had started at 6:45am, with the contrasting possibilities offered by a course measuring just 6,996 yards, and whose last US Open was 32 years ago, soon on show.

Cliff Kresge hit the first and opened with a par four, but playing partners Roger Tambellini and Ryan Yip both ran up double-bogey sixes on the 350-yard first hole.

Sweden's Rikard Karlberg posted the first birdie on the same hole a few minutes later only to run up a double-bogey seven on the second, while five-time US Open runner-up Phil Mickelson was also among the early starters after his cross-country trip, the left-hander having flown home to California on Monday.

Mickelson attended his daughter's eighth-grade graduation yesterday afternoon before flying back in time for his 7:11am tee time alongside Steve Stricker and Keegan Bradley, a bogey on the 11th soon cancelled out by a birdie on the 13th.

Colin Montgomerie had warned Sergio Garcia that he could be booed by fans in the wake of his "fried chicken" row with Tiger Woods, but the one person who did so half-heartedly on the 11th tee was drowned out by cheers and cries of 'Go get 'em Sergio.'

Garcia, playing alongside former Open champions Padraig Harrington and Stewart Cink, opened with a bogey but also birdied the 13th to get back to level par.