Joe Schmidt has given his players no indication of what the final Irish World Cup squad will be, according to lock Iain Henderson.
Ireland have a fairly settled side heading into the tournament, and have won the last two Six Nations under Kiwi Schmidt.
However the exact make-up of their 31-man squad remains a mystery, and with four warm-up matches still to come, Schmidt is keeping his cards close to his chest.
He will have to reveal his squad before the deadline on August 31, with Ulster second-row Henderson one of those battling to secure a spot.
"Joe is so hard to predict when it comes to selecting squads," Henderson told Press Association Sport.
"He keeps us on our toes at all times, so it's typical of him to be keeping us in the dark and that's what's happening now.
"It's making everyone work harder and harder all the time, and that in turn probably puts more pressure on him just to make those selections decisions.
"We're not even sure what the squad will be like for next weekend's game yet: Joe has kept us in the dark on that, and no doubt that's deliberate."
Ireland are in Pool D at the World Cup, where they will take on Canada, France, Italy and Romania as they seek to reach a World Cup semi-final for the very first time. Ireland are 7/1 outsiders with Betbright for the Rugby World Cup.