SYDNEY Swans coach John Longmire concedes last season's big improver Lewis Jetta is in a form slump, but says the club is working closely with him to solve his early-season troubles.

Jetta was nothing short of a revelation in 2012, leading the club with 45 goals and considered unlucky to miss All Australian selection as the Swans marched to the premiership.

It was always going to be a tough act to follow, with opposition sides trying to concoct ways to limit the impact of the super quick 23-year-old, who tore defences apart with his pace and tricks around goal.

And that has proven the case so for far this season.

Through four games, Jetta has kicked just two goals and averaged only 9.5 possessions.

His past two outings have yielded a total of 15 disposals, one goal and just 72 Dream Team points.

While the Swans were able to mask the issue with three straight wins to start the season, they suffered their first defeat in an uncharacteristically poor second half against Geelong on Friday night.

Longmire and the coaching staff know they face a challenging time trying to kick-start one of their most dangerous attacking weapons.

"Look he hasn't had the impact he had last year, so we need to keep working on it," Longmire said.

"There's no easy way out of that. When you're a young player, that's part of the challenges, bouncing back and going through form slumps, which tend to happen at times.

"It happens to the best players, but the experienced ones are able to get going again pretty quickly because they've been through it before.

"But we'll work with him, because we know his best is really good."

There are a number of selection headaches emerging for Longmire, who heads to New Zealand with his side on Monday morning for an Anzac Day showdown with St Kilda in Wellington.

Rhyce Shaw will again miss out with his abdominal strain, while Lewis Roberts-Thomson would be extremely unlikely to make the trip after sustaining a knee injury against the Cats.

With Alex Johnson sidelined for the year and the likes of Dane Rampe and Tony Armstrong struggling to cement a spot in the backline, Longmire has some tough decisions ahead.

He will take 25 or 26 players to New Zealand before deciding on his final team.

"I'd like to go back and have a look at the game," he said when asked to assess Rampe and Armstrong's performance against the Cats.

"I thought there was a 10 minute period in that third quarter we didn’t get the ball out as effectively from our backline as we should have.

"Not just those particular players, but we turned the ball over a couple of times, and they were able to kick a goal or two out of that.

"The gap between the style of footy we played and the style of footy we like to play was too great.

"That's probably the bottom line."