The Mariners weren't at the races against Melbourne Victory on Sunday night, losing 4-1 to the champions.

Trailing 3-0 at half-time, it looked a case of how many goals they'd ship until Mario Shabow put his side on the board.

Mulvey believed his side might have edged the second half but wasn't kidding himself, labelling the first half has unacceptable.

"The first 20 minutes I thought we were in the game ... and the soft underbelly reared its ugly head once again. The same as last week when we played against Adelaide," he said.

"(In the) second half we were the better team. I've just said to the lads, 'I can stand here and congratulate you on the second half performance which I thought was really bold' (because) they answered some of the things I asked about them at half time.

"But you've got to play two halves of football.

"You can't play 20 minutes, concede three goals and come alive in the second half. It's not good enough."

Antony Golec and Jacob Melling made several blunders, with only ex-Victory forward Connor Pain putting in a shift of note.

Tommy Oar left the match with a "knee tweak" but Mulvey said he should have no trouble contending for their next match - away to league leaders Perth - in a fortnight.

Mulvey suggested the shift that needed to occur in between now and then was mental.

"When I came here it was a club that accepting of failure. That's not good enough for any organisation," he said.

"We had quite a change at the end of last season when I first came in (though) we're still giving away the same opportunities for the opposition.

"We've got to stand up and eradicate those mistakes ourselves."

Australian Associated Press