On just his second A-League start, Sam Sutton crossed for roommate Ben Waine's injury-time winner in Wollongong on Sunday, giving the Nix their fifth win of the season.

As the game gathered pace in the second half, Western veteran Besart Berisha was heard in an effects microphone asking 19-year-old Sutton "who are you?"

"I think Besart will know who he is now," Phoenix coach Ufuk Talay said.

Wellington jumped one spot to ninth with the win and are seven points off sixth place in the finals race.

Talay appeared more excited by the potential for his youngsters to grow from that match-winning moment.

"That will be massive for both of them," he said.

"They've both played a very good game. They've both worked hard for the team. Waineo got in some good areas and I'm so pleased for him to score and Sutts to set it up."

Both sides played finals last season but came into the match in dire need of three points if they hoped to reach the playoffs again.

Berisha and Ulises Davila traded first-half penalties to send the sides into the break at 1-1.

The contest came to light in the second half, when Jaushua Sotirio nicked a goal by deflecting Davila's strike, and Iker Guarrotxena equalised with a close-range header.

The teams looked destined to share the points after Wellington missed a spree of late chances.

As the clock ticked into injury time, the two academy products combined for the winner, with Sam Sutton crossing for Waine to head past United 'keeper Ryan Scott.

The loss leaves United stuck in eighth, but with games in hand on almost every side above them.

Western United coach Mark Rudan worked with the pair during his 2018-19 season at Nix, and was highly charitable considering the hammer blow they struck his team.

"I'll allow Ufy to talk more about how happy he would have been ... but to see players you've worked with continue their professional careers, it's always pleasing," he said.

Rudan said Lachlan Wales was shaken after the match following a nasty head clash with Joshua Laws that led to his withdrawal.

Wales was originally allowed to play on after medical assessment, winning the penalty for Berisha's opener, before eventually being substituted.

"We've got a doctor back home in Melbourne as well who saw it and saw something more," he said.

"We felt it was the best thing for the player to come off.

"Player welfare is the most important thing, irrespective of a football game or the results."

Australian Associated Press