Darren Clarke carded a final-round 70 to end in a tie for 18th position on nine under par at the Italian Open.
Clarke's closing 18 holes included an eagle at the first, five birdies, a bogey and two double bogeys.
Ballyclare's Gareth Maybin fired an impressive 68 to finish in equal 46th place on six under.
South African Hennie Otto won on 20 under, with England's David Howell on 18 under and Scotland's Ryder Cup hopeful Stephen Gallacher 17 under.
Gallacher fell agonisingly short of the top-two position he needed to oust Graeme McDowell from an automatic place in the Ryder Cup team, so must rely on perhaps being awarded a wildcard from captain Paul McGinley on Tuesday.
Maybin posted an eagle, six birdies, two bogeys and a double bogey in his round as he continues his bid to retain his European Tour card.
Going into this week's event, Maybin was 124th in the Race to Dubai standings, some £27,000 behind the 110th spot which will secure a tour card for next season.
Ireland's Damien McGrane finished two under after recording a 71 on Sunday.
Clarke's best finish this season is a 24th spot at the Volvo Championship event in South Africa in January while he shared 26th at last month's Open at Royal Liverpool.