A penalty save by goalkeeper David Harte was not enough to rescue Ireland, who went down to Malaysia in their Olympic qualifier in Antwerp yesterday.
The lacklustre Irish were unpicked at penalty corners, with the set-piece routines providing three of their opponents' four goals in a desperately tight game.
Twice they equalised in the first half - a Peter Caruth deflection bringing them back to level terms on the first occasion and then a Shane O'Donoghue drag-flick restoring parity.
However, there was no comeback for a third time after Sukri Mutaliib knocked in a rebound at yet another corner eight minutes after the break.
Harte's heroics from the penalty kept Ireland in contention, but the quick-countering Malaysians pulled out of sight when Ahmed Tajuddin nicked their fourth following a quick counter-attack.
The disappointing failure to build on the 1-1 draw with Great Britain earlier in the week makes today's clash with China crucial if Craig Fulton's side are to retain any chance of qualifying for the Olympic Games in Rio next year.
They will certainly have to defend better to have any chance.
IRELAND - D Harte, R Gormley, C Harte, P Gleghorne, J Jackson, M Shimmins, M Darling, K Good, E Magee, P Caruth. Subs: J Bell, M Watt, C Cargo, C Sothern, S Dowds, D Carlisle, D Fitzgerald.