The second round of the British Open resumed on Friday after torrential morning rain flooded the Old Course at St Andrews, leaving many of the greens, fairways and bunkers under water.

Play had started at 6.32am but the first group, which included former champion Mark Calcavecchia, did not even complete the first hole before conditions became unplayable.

Around 100 groundstaff were trying to clear water from the course while the few brave fans who arrived early huddled in the exposed rain-lashed grandstands.

Sand bags were needed to prevent floodwater entering the media center.

"Staff have cleared a lot of the water so the course should be playable," David Rickman, the Royal and Ancient's head of rules, said.

"Golfers will have to play the ball as it lies but the casual water rule will apply. So players have free relief if their ball or their stance is in the water."

Casual water refers to water laying in bunkers and fairways.

While the rain is expected to relent for most of the day, winds are expected to increase throughout the day, with gusts of 35mph, according to the latest Met Office forecasts.

"The Old Course is very sandy and once it starts to drain it will do very quickly. If there is any course that can take this, it is the Old Course at St Andrews," R&A chief executive Peter Dawson said.

After Thursday's relatively kind scoring conditions, particularly in the morning, the second round looks like becoming a real test for the world's best players.

"The guys who have been delayed and are going out now may have an advantage, especially if the wind gets up later," Europe's former Ryder Cup captain Mark James told the BBC.

Saturday's forecast is for even stronger winds, with gusts of around 50mph, meaning the R&A could face a difficult task to get the tournament finished on schedule by Sunday.

The second round is likely to spill over into Saturday.

"It could be Armageddon-type stuff by the looks of the weather forecast," Britain's Danny Willett who shot a first-round 66 to lie one stroke off the lead held by American Dustin Johnson," said.

"When the wind and rain gets up it can be a lottery."

The Open was also hampered by bad weather when it was last held at St Andrews in 2010, with dangerous high winds creating havoc in the second round.

(By Tony Jimenez; Additional reporting by Martyn Herman; Editing by Sudipto Ganguly)