Adam Scott won’t arrive at Augusta National as world No.1 for his Masters defence next month after blowing a big lead at the Arnold Palmer Invitational.

For all his successes, last-day stumbles are proving very costly for Australian golf ace Adam Scott.

Once a fearsome frontrunner, final round fadeouts have denied Scott a British Open crown in 2012, the Australian Open trophy in 2013 and now the world No.1 ranking.

Scott’s sloppy four-over-par 76 at the Arnold Palmer Invitational was his worst round of the year in his most important one.

More than denying the 33-year-old his 11th victory on the US PGA Tour, Scott would have headed to his Masters title defence next month as world No.1 had he won, presuming he and Tiger Woods sat out the next two tournaments as scheduled.

The manner of Scott’s latest collapse was all too familiar and must be a confidence blow for the Queenslander.

His Sunday shocker was eerily similar to his capitulation at Royal Lytham and St Anne’s two years ago when Scott had one hand on the Claret Jug, while the round also featured shades of his near miss at Royal Sydney last December.

Heading into the final round at each of the three events with big leads, Scott couldn’t buy a putt.

His 33 putts and five bogeys at Bay Hill opened the door for American Matt Every to secure his maiden US PGA win and a ticket to the Masters, where Scott must be content to defend his title as world No.2.

“Sometimes you have to be hard on yourself,” said a frustrated Scott. “Sometimes you don’t.

“I was getting into a good spot and had the opportunity to run away with an event and really take a lot of confidence.

“Some opportunities you’ve got to take.”

While Scott collected 15 of his first 18 worldwide victories from in front, five of his past eight wins – including his historic Masters triumph – have come after he trailed heading into the final round.

On the biggest stages, Scott has been unable to protect a lead entering the last round since his infamous meltdown at Lytham.

After opening with a course-record 64, Scott carried a four-shot advantage into the final round at Lytham only to card a five-over 75 on Sunday to lose by one.

Bidding to complete the Triple Crown of Australian golf at Royal Sydney, Scott birdied the first six holes en route to a sizzling 10-under 62 on day one, the same first-round course-record equalling score he shot at Bay Hill on Thursday.

But he blew a four-shot final-round lead to again lose by one.

With tournament host Arnold Palmer watching on, Scott again seemed destined for a wire-to-wire victory on Monday (AEDT) before unravelling.

He led by eight shots after 35 holes and by seven after firing a record 14-under halfway total.

But with his broomstick putter failing him once more, Scott allowed Every to sneak under his guard with a final-round 70 to prevail at 13-under, one ahead of fellow American Keegan Bradley (72), with Scott third two strokes back.

A snapshot of his round came at the par-5 15th where his 19-foot eagle putt for a share of the lead shaded the cup and then he missed the return effort for birdie.

“I really think the putting let me down,” Scott said. “I am annoyed I didn’t putt at all today. Poor, just out of sorts for whatever reason.”