BANGKOK, July 16 (Reuters) - Australia put a dismal start to their first Asian Cup campaign behind them by thrashing co-hosts Thailand 4-0 to reach the quarter-finals on Monday.

Captain Mark Viduka scored two late goals in a ruthless

display by the Socceroos which set up a mouth-watering

last-eight clash with Japan.

Michael Beauchamp opened the scoring from a set-piece in

the 20th minute before captain Viduka sealed victory with goals

in the 79th and 83rd minutes.

Harry Kewell completed the rout with a goal in the last

minute of normal time, confirming the one-time tournament

favourites' return to form.

The two teams finished Group A level on four points in

second place but Australia went through as runners-up based on

their head to head result.

Iraq finished top of the group standings after playing out

a scoreless draw with Oman. Iraq play Vietnam in the

quarter-finals.

The Socceroos were in danger of an embarrassing early exit

from the tournament after drawing 1-1 with Oman and losing 3-1

to Iraq but found their form in the nick of time at a packed

Rajamangala stadium.

After struggling to cope with the heat and humidity in

their previous games, the Australians could not have asked for

better conditions with the match played at night in steady

rain.

Coach Graham Arnold reacted to his team's loss against Iraq

by making four changes to his starting lineup and his

selections were vindicated when Beauchamp headed a

perfectly-weighted free kick from Luke Wilkshire past Thailand

goalkeeper Kosin Hathairatanakool.

Australia's superior height gave them a distinct advantage

in the air but they struggled to maintain possession long

enough to create many opportunities.

Thailand had more chances but poor finishing and desperate

Australian defence kept them scoreless even after the

introduction of playmaker Datsakorn Thonglao, who was married

on Sunday and started on the bench.

Sutee Suksomkit almost scored in the seventh minute when he

curled a cross from the left that beat Australian keeper Mark

Schwarzer but floated past the far post.

Substitute Pipat Thonkanya had a great chance to equalise

midway through the second half when he shot from inside the box

straight at Schwarzer and Suchao Nutnum unleashed a powerful

long range drive that went just wide.

After soaking up the pressure for almost an hour, Australia

caught Thailand on the counter-attack with Newcastle striker

Viduka completing a quickfire double before Liverpool's Kewell

scored a fine solo goal to add gloss to an impressive win.