Newcastle Jets coach Ernie Merrick blamed fatigue from a hectic schedule and not defensive blunders or the video referee (VAR) for his side's 3-2 loss to cellar-dwellers Wellington at McDonald Jones Stadium on Saturday.
Second-placed Newcastle, aiming for a club record fifth consecutive home win, missed early chances and were down 2-0 at halftime in the round 17 game after late replacement Jack Duncan was caught out twice in goals.
Andrew Nabbout scored in the 48th minute to give the hosts hope but Phoenix made the most of another opportunity to go 3-1 up in the 58th.
Roy Krishna scored while the Jets were down a man when centre-back Nigel Boogaard was off the field getting a head cut stitched and strapped.
Newcastle rallied late when Dimi Petratos scored from the spot in the 86th minute after substitute Angus Thurgate was fouled.
Referee Jarred Gillett reviewed the penalty call and Marco Rossi was shown to commit the slightest of shirt tugs.
Thurgate then went down in the box after contact with Andrew Durante in injury time but Gillett waved away penalty calls before the VAR stuck with the on-field decision.
Duncan, back from a foot injury, replaced Glen Moss in the starting side after he aggravated a hip flexor problem in the warm-up.
He misread Serbian midfielder Matija Ljujic's ball for Wellington's opener in the 28th minute and ran into his own defender when Daniel Mullen scored with a header from a corner in the 36th.
Merrick, though, refused to lay the blame with Duncan or the decision to play on without Boogaard.
"Making mistakes is a part of learning, so Jack Duncan will understand that, but I thought Jack did pretty well," Merrick said.
"It didn't come down to Jack having a good game or a bad game or Nigel Boogaard being off briefly.
"It came down to an overall performance that really lacked consistency from beginning to end.
"... I think overall it was a pretty flat performance. I think playing four games in just over two weeks finally took its toll, but it was a credit to the boys that we worked hard right until the end."
Of the VAR calls, Merrick said: "The decisions from the VAR were quick. I haven't really been able to see a replay of what occurred but those things happen in football. You win some, you lose some."
Phoenix coach Darije Kalezic was pleased with the performance and the proactive impact of January recruits Nathan Burns and Matija Ljujic, who started for the first time against Newcastle.
"We played really solid from the beginning," Kalezic said.
"I have to say they created a couple of chances in the first half but we came through without any damage from that period and then we wait for where the weakness of Newcastle was and we were looking to punish them from that point and that's what we did."
The Jets will retain second spot on 33 points. Phoenix move to 14 but remain in last spot.