I did a Malaysia Airlines flight of similar duration (AKL - KUL) on a B772 a couple of years back. On the deck were 2 Captains, one FO and one SO. When I went up there both Captains were there and the FO was asleep in first class, SO was having a meal elsewhere (this was about 5 hours into the 11 hour flight). I think one Captain was heading for a rest break once the SO was back. Don't know if they always have four, but would guess at least three.