Masters 2014: Bubba Watson feeling liberated without defending champion tag

Although he does not drink, Watson admits he suffered from a hangover of sorts following his win in 2012, given his unusual background for a professional golfer.

"You've got to think about where I've come from, my mom having two jobs to pay for my golf, my dad working in construction," he added. "And when you think about that and where I am in my career, you're thinking about how great this was.

"It's an accomplishment for a guy named Bubba, with my mom, my upbringing. My year, my career was complete after that win so obviously I was going to have a hangover. Never been drunk before, but a hangover from the green jacket.

"I do everything my way. I learned the game my way, figured it out my way. So it just takes me a little bit longer with the mental focus and drive to get back to where I am today."

Bjorn had been 51 over par for his previous 10 Masters appearances before rounds of 73 and 68 this week, the 43-year-old Dane recording four bogeys and eight birdies, four of them coming in the last five holes.

"I played well all the way through and felt comfortable on the golf course today," Bjorn said. "I hit two great shots into 13 and walked off with a par and after that decided I needed to be more aggressive. I took the shots on at 14 and 16 and they paid off and it was nice to walk up and tap it in for a birdie on 18."

Scotland's Stephen Gallacher was also delighted with his second round, a 72 leaving him one under and guaranteed to make the halfway cut on his Masters debut - something his uncle Bernard, the former Ryder Cup captain, was unable to do in 1970.

"I'm delighted to still be in red numbers to be honest," Gallacher said. "It was a bit tricky, the wind is a bit up and the greens are firming up. It's a very strategic course. I think everybody back home knows how to play it, it's just a case of trying to do it, that's the hard part."

Former Open champion Louis Oosthuizen, who lost a play-off to Watson in 2012, held a share of the lead when he holed from five feet for an eagle on the 13th.

But the South African then ran up a triple-bogey eight on the 15th after chipping from the back of the green into the water at the front, before a bogey on the 18th meant a round of 75 and left him level par for the tournament.

Three-time Masters champion Phil Mickelson was in danger of a first missed cut since 1997 after a triple-bogey on the 12th, where he amazingly went from the front bunker to the back bunker and back into the front bunker again.

A 73 left Mickelson five over par, but playing partner Justin Rose - who was six over after 12 holes on Thursday - bounced back from an opening 76 with a round of 70 to lie two over, as did Ryder Cup team-mate Ian Poulter.