Ireland suffered a 4-2 defeat to Belgium on Saturday in the first of two warm-up matches ahead of their World League 3 campaign later this month.
Shane O'Donoghue scored twice at the Dragons Hockey Club in Belgium, after the hosts had raced into a 3-0 lead with Dohmen, Boon and Luypaert goals.
O'Donoghue's drag shot got Ireland on the scoresheet after 21 minutes, and he scored his second ten minutes later.
Dockier's deflection sealed Belgium's win and the teams meet again on Sunday.
Belgium, the world number four seeds, are the top-ranked team in Ireland's Pool at World League 3 when the Irish will step up their bid to qualify for the 2016 Olympic Games in Rio.
After a bad start, they recovered well against the home side, who will also host the World League 3 tournament which begins on 20 June.
The Irish were slow to settle in new surroundings at the Dragons club and were 3-0 down by the end of the first quarter.
However they dominated possession in the second quarter and reduced the deficit further in the third quarter with O'Donoghue's second strike from a penalty corner.
A Belgium breakaway down the left took an unlucky deflection off an Irish stick to restore a two-goal cushion for Belgium.