Merrick's Newcastle Jets are among the hardest hit by the Australian U/23's two week  camp, losing Ivan Vujica, Johnny Koutroumbis and Joey Champness to the AFC U/23 Championship qualifiers.

While all three have played a significant role in five matches (including friendlies) over the congested period, in humid South-East Asian conditions, Vujica in particular has starred at the tournament.

Merrick, however, isn't wrapped with the international experience, criticising the way the league is structured.

"The Olyroos play three games in five days," Merrick said.

"So if any of them play 90 minutes in the third game, it's questionable to see how fit they're going to be on Saturday. We're taking a squad of 18 to (our next game) Wellington Phoenix, rather than 16.

"I understand the role of the national coach and what he's trying to achieve but I thought the international break would mean we don't need to lose players.

"While the bigger teams can sign players, sometimes they get assistance in the form of half a million dollars to sign another marquee, the sides that are developing players are the ones that get hit.

"The system is broken, but I don't know how you're going to present that."

Merrick is one of many to raise doubts over whether removing an almost-entirely A-League based squad from competition for the qualifying tournament is a good idea, with balancing the impact on clubs against the international experience (and possibility of qualifying for the Olympics) a sticking point.

Merrick has much more pressing concerns than the future of Australian football though, seventh-placed Newcastle are within a hair's whisker of missing out on finals football entirely after challenging in the A-League Grand Final last season.

"We've had three days off and I think they all thought they had today off, it was pretty sluggish but that's to be expected," Merrick said.

"I spoke to the senior players at the end and told them they have to take responsibility for players not giving their all, not just me. 

"Next two days we'll be ramping it up, play a larger game on Wednesday, travel, train and then take on Wellington.

"They've been good at bouncing back but it's all or nothing from now on. It's easy as that, we've just got to win and that's what we're going to do, we've got the players for it."

Merrick face Wellington in what a few weeks ago promised to be a do-or-die finals clash for sixth position. However, the Nix have shot up the table after a mid-season slump and are now as close to Melbourne Victory in third, as the Jets in seventh.

"There's no second chances anymore, Wellington have done well and they've pulled away a couple of points, but we're up for it and still in with a chance," Merrick concluded.

"We've got to win three, draw one and maybe lose one.

"We've got to raise our training standards and be clinical around the goal area. The senior boys are on field leaders and have to lead on and off the park."