The former world No1 was humbled in Humble, Texas, when he rounded out an otherwise promising tune up at the Houston Open with a double bogey and a quadruple bogey on his last two holes finding the water twice on the 18th.

Australia's Nick O'Hern boosted his morale with a tie for third behind winner Paul Casey while Norman now heads to Augusta National for his return to the Masters, after a seven-year absence, with a back nine of eight-over 44 fresh in his mind.

The 54-year-old part-time tour pro had shown plenty of good signs during the week at a tournament where conditions were set up to replicate the Masters.

But he came unglued on the brutal closing holes of the Redstone course as he equalled the day's worst score of 81 to tumble from tied 26th after the third round to a share of 70th among 78 players who made the cut.

Bogeys at the 11th, 12th and 14th were followed by a birdie at 15 before a double bogey at 17.

And Norman capped it with an eight on the par 4 18th when he hit in to the water twice, once on his lay-up shot and then again on his approach.

Englishman Casey notched his maiden US PGA Tour win when he overcame American JB Holmes in a sudden death play-off.

It was the first win in 52 starts on the US tour for Casey, who led by one with one hole to play but bogeyed the 18th in regulation to shoot even par 72 and finish at 11-under 277.

Casey also bogeyed 18 in the sudden-death play-off, but that was enough to see off Holmes, who drove his tee shot into the water.

O'Hern shot a 70 to tie for third place at nine under with Sweden's Henrik Stenson (70) and American veteran Fred Couples (74).

Geoff Ogilvy was tied for the lead after the third round earlier in the day but slipped to tied sixth at eight under after a closing 75. AAP

73RD MASTERS TOURNAMENT

At Augusta National Golf Club, Georgia from Friday to Monday. TV Time: Live daily on Ten from 6-9am.