Changes to the All Blacks line-up from one rugby Test to next is having the desired effect, coach Wayne Smith says.

Players worked harder as a result to try to make the starting 15 and that meant the pressure was on the entire squad to perform each week, he said.

The ``trials'' however are expected to end after Saturday night's match against Argentina in Christchurch.

Smith plans to name his top 15 from a squad of 24 for the Test against France in Wellington next Saturday and maintain stability to his selection for the tougher Tri-Nations and Bledisloe Cup Tests ahead.

``That has been the plan right through, we haven't diverted,'' Smith said. ``The individuals know the pressure is on, that's competition - the heat's on.

``Probably inside themselves they're not happy because they don't get all the games. But sometimes you have to get out of your comfort zone to make improvements and they're hard enough.

"They just have to accept it and get on with it. There's got to be a lot of trust in any team, and we trust the players and they have to trust as well that we're doing the right thing for the team.''

After last week's 50-6 win over Samoa, Smith made six changes for Saturday's match, bringing back recent All Black regulars Jonah Lomu, Justin Marshall, Andrew Mehrtens and Taine Randell into the team.

The newcomers are No 8 Jerry Collins and prop Carl Hayman, although Hayman made his debut off the bench against Samoa.

Lomu said he felt hard-done-by after his exclusion from the Samoa Test. ``I could have spat the dummy, but that couldn't have done me any good,'' he said.

"You get your ups and your downs, but you have to do what's best for the team. In their (selectors') minds they have a set task and a goal to put more trophies back in the cabinet and I definitely want to be part of that. If it means missing a game, then it means missing a game.

``The point I have to prove is that I want to be in the starting line-up every week.''

Smith seems to be searching for the best openside flanker, No 8, tighthead prop and a lock and a wing.

Leon MacDonald has been given another chance to prove himself at fullback in the absence of Christian Cullen, who is recovering from a knee operation.

Randell, who starts at openside flanker, has Marty Holah as a rival, newcomer Jerry Collins and Ron Cribb are the No 8 contenders, Carl Hayman and Greg Somerville vie for tighthead prop, Mark Cooksley will be considered for lock - Norm Maxwell and Troy Flavell are Saturday night's locks - while Jeff Wilson and Doug Howlett vie for right wing.

A much-improved Argentina should test Saturday night's side in the forwards with nifty halfback Augstin Pichot snapping at their heels.

``Everyone knows about their forwards. Their backs showed very good ability on the draw-and-pass (against Counties-Manukau last Sunday), they used the blindside well and they're very straight and tricky, plus they defended well,'' Smith said of the Pumas.

The Argentine game is based around their powerful scrum and Pichot. ``He's the spiritual key to them, looks to be the soul of the team.

"He does a lot of the talking, he does a lot of the organising. He's cheeky, he's world-class and he's someone we've got to stop,'' Smith said.

A top effort was expected from Mehrtens after the flyhalf missed most of the Super 12 season through a groin problem.

``We want a strong defensive effort from him, because he's in a critical position there,'' Smith said. - Sapa-NZPA