Tiger Woods' charge was halted by an approaching thunderstorm as the 83rd Masters crackled into life on the second day at Augusta National.

Woods had just recorded the first birdie of the day on the daunting 11th hole and fired a superb tee shot to five feet on the 12th when the siren sounded to suspend play due to the threat of lightning.

After a delay of around 30 minutes play was able to resume and Woods missed the birdie attempt to remain four under par, three shots off the lead shared by Open champion Francesco Molinari, Jason Day and Brooks Koepka.

Former world number one Dustin Johnson and South African debutant Jason Harding were also safely in the clubhouse on six under, with England's Ian Poulter a shot further back after a 71.

Molinari had to wear a white boilersuit on his first visit to the Masters as caddie for his brother Edoardo, but put himself in position to leave this time with a coveted green jacket thanks to a flawless 67.

"I didn't learn much about the course because we were going sideways most of the time," Molinari joked in reference to Edoardo shooting rounds of 80 and 77 to comfortably miss the cut.

Molinari made his debut as a player in 2010 and recorded his best finish to date with a tie for 19th in 2012, but came into the event on the back of a stellar 12 months.

The 36-year-old has won four times since last year's Masters, including the Open Championship at Carnoustie, while he also became the first European player to earn a perfect 5-0 record in the Ryder Cup in Paris.

Beginning the day four shots off the lead, Molinari birdied the third, eighth and ninth to reach the turn in 33 and picked up further shots on the 12th and 15th before a superb two-putt from 75 feet for par on the last.

"It was good, pretty solid, not many mistakes and when I missed greens I missed them on the good side, leaving myself pretty easy up and downs so all in all a very good day," Molinari said.

"Now I'm just going to rest. The game is in good shape so I don't think I can gain much from hitting balls. Just get as much energy as possible for the weekend. There's going to be a lot of players in the mix and a very long way to go."

Day had needed on-course treatment for a back injury during the first round, but completed an opening 70 and matched Molinari's 67 on Friday thanks to six birdies and a solitary bogey.

Poulter enjoyed a massive slice of luck when his approach to the 13th stuck in the bank of Rae's Creek and allowed him to chip and putt for an unlikely birdie, but added: "I'm a little frustrated with a couple of missed opportunities towards the end there.

"But it's on the board and I am in position and it's going to be a good weekend. There's a long way to go and if you put yourself in position with nine to go the course opens up. As long as I am there or thereabouts and try to be super aggressive who knows what can happen."

Rory McIlroy was six shots off the lead when play was suspended, the Northern Irishman kickstarting his bid for the career grand slam with an eagle on the par-five eighth to move to one under par.