Depleted, yet delighted. The Wellington Phoenix approach the second leg of their A-League soccer road trip in buoyant mood after a ground breaking triumph in Adelaide that allows them to determine their own destiny.

A historic success on Adelaide United's soil last night, a coveted 1-0 scoreline at Hindmarsh Stadium, incorporated several feel good factors for the club, most notably tightening their grip on the sixth and the final playoffs spot.

By achieving consecutive wins for the first time this season - and only their second victory on the road since Perth on November 7 - the Phoenix are in the box seat to progress to the finals series for a second successive year with two matches remaining.

They play Sydney FC on Wednesday and then return to the sanctuary of Wellington to play lowly North Queensland, where a win in front of the faithful will be sufficient.

Melbourne Heart dropped out of the race thanks to Chris Greenacre's diving header gave the Phoenix the win, leaving Newcastle and Sydney FC, who meet tonight, as the only other clubs still remotely in contention.

Greenacre initiated just the Phoenix's second win outside of Wellington in 14 attempts this season, a fitting way to celebrate the club's 100th A-League game.

"We're in the box seat now, we've set ourselves up really good," captain Andrew Durante said.

"We haven't had a lot of luck on the road and at times we've been poor as well but at the business end of the season we've knuckled down and got a great result. Mentally it's massive for us.

"If we do make the semis it looks like we'll have to go back to Adelaide so to grind out a 1-0 is going to put us in good stead."

There were downsides, however.

Durante, the heart of the defence, will not be available until the playoffs after collecting an eighth yellow card for handling the ball in the 80th minute.

"It put a dampener on the night but in the back of my mind I'm glad I got it now and not the week after. I'd be gutted if I had to miss a semifinal game," he said.

Durante's enforced absence and the suspensions already being served by Manny Muscat and Ben Sigmund mean 18-year-old defender James Musa will start against Sydney in what will be just his third appearance of his debut season.

A replacement will also be summoned from Wellington after midfielder Vince Lia was ruled out of Wednesday's game due to a hamstring strain sustained last night.

Still, those setbacks could not take the gloss off a Phoenix performance that stirred happy memories for Durante.

"Last season we went on a really strong run at the end of the season and we seem to be doing that again."

On their last away trip - to the Brisbane Roar on January 26 - the Phoenix held the title favourites at bay until conceding two late goals.

"We were well organised again, we had a gameplan to frustrate them and they didn't really cause us too many problems," Durante said.

Adelaide United coach Rini Coolen, whose side can now finish no higher than third, reiterated his concerns about scheduling after being lumped with three games in a week, including a match on the Gold Coast played in 94 per cent humidity last Wednesday.

"We have three, four or five players with muscle problems and (who) couldn't train because of the travel schedule," he said.

"It's not good for the players, it's dangerous."

The Phoenix endured a similar programme when their game against the Roar was postponed due to the Queensland floods and Durante realised Adelaide would be lethargic.

"We knew they'd be heavy legged. Three games in a week is tough. We wanted to get them on the back foot early. We did that, we got a well worked goal them we shut up shop."