Americans threatening early at Open Championship – in pictures

Phil Mickelson of the US tees off at the second hole on Thursday during the first round of the 2015 Open Championship. Mickelson finished the day 2-under, tied for 24th. Andrew Redington / Getty Images

United States fans show their support during the first round of the 2015 Open Championship at St Andrews in Scotland on Thursday. Stuart Franklin / Getty Images

Tiger Woods of the US reacts as he walks off of the 18th green during the first round of the Open Championship on Thursday at St Andrews. He struggled at 4-over for the day, tied for 139th. Streeter Lecka / Getty Images

A mobile scoreboard displays Tiger Woods's troubles on the opening day of the 2015 Open Championship on Thursday. Glyn Kirk / AFP

Robert Streb of the US hits his tee shot on the 18th hole during the first round of the Open Championship on Thurdsay. Finished tied for second at 6-under. Russell Cheyne / Reuters

US golfer Zach Johnson walks onto the 16th tee during his first round 6-under performance to tie for second in the opening round of the 2015 Open Championship on Thursday. Adrian Dennis / AFP

Paul Lawrie of Scotland watches his tee shot on the first hole during the first round of the Open Championship on Thursday at St Andrews. He finished the day tied for second at 6-under. Lee Smith / Reuters

Danny Willett of England reacts after making his birdie putt on the 18th hole to finish the day 6-under at St Andrews during the first round of the Open Championship on Thursday. Paul Childs / Reuters

German golfer Martin Kaymer shown on the course during the first day of the 2015 Open Championship on Thursday. Kaymer finished 1-under, tied for 40th. Facundo Arrizabalaga / EPA

Louis Oosthuizen of South Africa tees off on the 12th hole during the first round of the 2015 Open Championship on Thursday at St Andrews. He finished 5-under, tied for eighth. Matthew Lewis / Getty Images

US amateur Jordan Niebrugge plays out of the sand at the 16th hole on Thursday during the opening round of the Open Championship. He finished tied for eighth at 5-under. Stuart Franklin / Getty Images

Kevin Na of the US chips onto the 17th green during the first round of the 2015 Open Championship at St Andrews. He finished the round 5-under and tied for eighth. Stuart Franklin / Getty Images

Rickie Fowler of the US tees off on the 13th hole on Thursday during the first round of the Open Championship at St Andrews. He finished even par, tied for 65th. Streeter Lecka / Getty Images

England’s Justin Rose lines up a putt on the 13th green during the first round of the 2015 Open Championship on Thursday at St Andrews. He finished tied for 40th at 1-under. Jon Super / AP

Images from the first day of the 2015 Open Championship, where US golfers like Dustin Johnson (7-under), Robert Streb (6-under) and Jordan Spieth (5-under) surged to the top of the leader board early on. Click the arrows below to scroll through the photos.

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