Following their surprise victory over Australia earlier in the day, Ireland put up another commendable performance before going down 17-5 to Portugal.
The sides were tied five points apiece at the break thanks to a Paul Marshall
try but in the second half Portugal ran in two unanswered tries to emerge top of their group and set up a Plate quarter final tie with Canada.
For their part Ireland now play Arabian Gulf in the Bowl quarter final.
Argentina, Fiji, South Africa, Samoa, New Zealand and England will contest the Cup quarter finals.