United were dealt a blow midweek with Fyfe's partner in the centre of defence, Nigel Boogaard, seriously injuring his ankle at training. Boogaard is expected to be sidelined for three months.

The Reds also have central defender Robert Corthwaite on the injured list after a groin injury has seen him miss all of pre-season and his return wasn't scheduled for another month, although, now he may be rushed back into the side.

Fyfe admitted he will be taking on extra responsibility this week against the Mariners who were the only team to record a win in Round 1 after beating newcomers Melbourne Heart 1-0.

"It's going to be hard," Fyfe said. "We've got players out, important players for our team.

"Nigel getting injured isn't going to help us obviously, we're just going to have to make do with what we got.

"We've worked a lot on our shape, different players in different positions this week, but we'll be alright.

"I think it's my responsibility every week to get the defence up for every game and this week will be no different no matter who we play back there."

Fyfe empathised with Boogaard, who celebrated his 24th birthday on Saturday and was due to meet his former side on Sunday.

"It would have been nice for him, he was looking forward to it," he said.

"But he knows these things happen. You roll your ankle on the pitch and unfortunately players get injured when you play professional sport.

"He's gutted, he's obviously gutted but he's got to look towards getting fit and getting back in the team."

The former Sydney FC stopper admitted that right back Daniel Mullen will partner him in defence in the absence of Boogaard and Cornthwaite, conceding there wasn't really any other option.

Fyfe tipped either Adam Hughes or Paul Reid to replace Mullen on the right side of defence.

"I think that's pretty obvious. We don't really have anyone else to fill that void," he said.

"Daniel Mullen has played there before, I've played with him before, we're a good partnership and we worked on it all week.

"He's a good player, he's strong, got good technique, he's good in the air and he'll be very good next to me.

"We've tried a few players there but it's the coach's call in the end. From what I can tell it's probably going to be Hughesy, but also Reidy, he's played a couple of games there back in England so we've got a number of players that can play in that position, but probably Hughesy will fill that void."

The 28 year-old acknowledged the injury crisis at United is frustrating and conceded new coach Rini Coolen hasn't had the ideal start and preparation to his A-League coaching career.

The Dutchman was already without captain Travis Dodd who underwent groin surgery in the off season and may not return to action for another two months, Fabian Barbiero missing with an ankle injury and Lloyd Owusu (knee) whose stint on the sidelines is still indefinite.

"I think it would be more frustrating for Rini," he said.

"Obviously he has a plan he wants to achieve eventually and it doesn't help with all the injuries every week. More and more players getting injured doesn't help but we get on with it."

Fyfe said the Mariners will be a tough task, especially with new coach, former Socceroo boss Graham Arnold at the helm and on their home turf.

"It will be a pretty big challenge, Central Coast are always strong at home," he said.

"They look like a well drilled outfit. Graham Arnold has got them in good shape, they work very hard and they've added a little bit of flair as well and I think we saw that against Melbourne Heart.

"We'll have our work cut out for us I'm sure."