by Mark Stokes

Darren Clarke resisted an American charge to claim the outright lead after day three of the 140th Open at Royal St George's, Sandwich on a day of wildly fluctuating weather.

The joint overnight leader, who began the day on -4, made the most of easing conditions in the afternoon to shoot a one-under par 69 - giving him a three-round total of 205.

Leading the American challenge was new bookmakers' favourite Dustin Johnson, who fired four birdies on the back nine to card a two-under 68 - and finish just one shot behind the 42-year-old Irishman.

Clarke began his round just after 3pm, and not long after the rain ceased and the winds dropped. He began well by picking up a birdie at the first but he went back to four-under after a bogey at the fifth. A second birdie came at the seventh but he immediately bogeyed the eighth, leaving him on 35 at the turn.

Hitting the ball superbly, Clarke was near faultless from the tee on the back nine, supplementing a birdie at 12 with pars at the remaining holes to make 34.

Johnson - who hit a hole-in-one on the opening day - went to the turn in 35 as bogeys at four and nine were cancelled out by birdies at five and seven.

The 27-year-old from South Carolina had two more bogeys on his back nine, but birdies at 10, 12, 14 and 15 put him right in the frame.

First day leader Thomas Bjorn, of Denmark, remains in contention on - 2 after shooting 71 (35/36) and he is joined on that score by the big mover of the day, Californian Rickie Fowler, who outshone his playing partner, US Open champion Rory McIlory, with a superb 68 in the worst of the day's conditions.

Both 22-year-olds started the day even, but while McIlroy struggled for fluency his American rival upstaged him by becoming the first man to break par.

Fowler had just one birdie in his outward half of 35, but hit a purple patch on the back nine with birdies at 13, 15 and 16 for an inward 33.

McIlroy in contrast made just one birdie - at the seventh - and collected three bogeys, plus a double bogey seven at the 14 to finish on 74 (37/37).

Behind Bjorn and Fowler, on -1, are Spaniard Miguel Angel Jimenez, and American Lucas Glover, who had shared the lead with Clarke overnight.

Neither man managed a birdie, with Jimenez's 72 (37/35) featuring two bogeys, and Glover's (35/38) three.

Only six players came in under par on the day and at one stage the top 16 contained 12 Americans, with leader Clarke and Englishman Simon Dyson the only Brits to break into the top 30.

Umbrellas and waterproofs had been very much the order of the day in the morning as the weather took a significant turn for the worse.

Driving winds and unrelenting rain made conditions uncomfortable for competitors and spectators alike and it soon became clear that any birdie would be a bonus.

The tone for the morning was set by 35-year-old Australian qualifier Matthew Millar, who went out first, on his own, at 8.55am and collected just one birdie on his way to a 10-over total of 80, putting him13-over for the tournament.

Paul Lawrie, the last British winner in 1999, fared even worse, going round in 81 (+14), despite picking up a rare eagle at the 564–yard par five seventh.

By mid afternoon still no-one had shot par, with the best score of 72 (two over) being achieved by South African Trevor Immelman and American veteran Tom Watson, who once again rolled back the years much to the delight of the rain-soaked crowd.

Immelman started with two bogeys but clawed it back with birdies at seven and nine, for an outward of 35. He also had two bogeys on the back nine, but was level for the remaining six holes to finish in 37.

Watson, 61, reached the turn one-under in 34, having strung together eight pars, plus a birdie at the seventh. He found things a bit tougher on the back nine, with bogeys at 11, 12, 15 and 18 but a birdie at the 16 saw him home in 38.