The Mariners have missed their past four spot kicks, including three in a row last week.

McBreen was responsible for the first two misses before passing on the role to Nick Montgomery for last week's AFC Champions League clash with Suwon Bluewings.

Montgomery missed as well, and then on Saturday goalkeeper Mathew Ryan stepped up and had his attempt saved as the Mariners' unbeaten home record in the A-League ended following a 1-0 defeat against the Western Sydney Wanderers at Bluetongue Stadium.

Should the Mariners get another penalty against the desperate Sky Blues on Saturday, expect McBreen to step up.

"He is a striker and has scored some good penalties for us this season," Arnold said, as his team look to get their A-League title charge back on track.

"He lost a bit of confidence after missing a couple but I believe he will step up and take responsibility. I'll have a chat with him this week."

With new competition leaders Western Sydney showing no signs of a late-season lapse, the Mariners cannot afford another slip-up if they want to claim another Premiers' Plate for a third time in eight seasons.

"We had enough chances to win last week," Arnold said.

"At this time of the season every game is important. We'll have a good week of training and be ready for Sydney."