Colin Montgomerie could miss out on the 2008 Masters after dropping out of the world's top 50.
Montgomerie began 2007 ranked 17th in the world
The Scot has slid from 17th to 57th in the rankings in 2007 and will need to re-enter the top 50 the week before the 10-13 April event at Augusta, Georgia.
The eight-time European number one could also make the year's first major by winning a US Tour event.
Other Europeans already in the Masters field include Justin Rose, Luke Donald, Padraig Harrington and Sergio Garcia.
Rose, Donald and fellow Englishmen Paul Casey and Ian Poulter qualified by finishing in the top 16 at this year's Masters, though they are also well inside the top 50.
Nick Dougherty, ranked 48th, also qualified for his Masters debut courtesy of his seventh place at this year's US Open.
Lee Westwood, Denmark's Anders Hansen and Soren Hansen, Swedes Niclas Fasth, Henrik Stenson and Robert Karlsson, and Spaniard Miguel Angel Jimenez also clinched places at Augusta.
Anders Hansen will make his Masters debut after clinging on to 50th spot in the standings by just 0.01 points with no more ranking events to come this year.
He could have lost his place to Robert Allenby, who shared the lead with a round to go in the Australian Open before closing with a 75 to drop to 11th place and down to 51st in the rankings.
Former champions Bernhard Langer, Sandy Lyle, Jose Maria Olazabal and Ian Woosnam will also line up in Georgia.
Montgomerie failed to qualify for the Masters in 2005 following 13 straight appearances at the event since his debut in 1992.
The 44-year-old has missed the cut at Augusta for the last two years, and his best finish remains tied eighth in 1998.
The defending Masters champion is Zach Johnson, with Tiger Woods again the favourite to capture his fifth green jacket.