Youngster Matthew Lewis and veteran Andrew Clark are both in the running for a start at left back for the clash.

Regular left back Dean Heffernan is suspended for the crucial match at Bluetongue Stadium meaning an opportunity has opened up for someone else to impress.

Clark has been a utility player for the Mariners this season, but has been unable to cement a regular place in coach Lawrie McKinna's squad despite several strong performances off the bench.

Lewis started last week's 3-0 loss against Melbourne but was found out defensively in the second half against the competition leaders.

"I'm still to finalise what we'll be doing to replace Heff but there's options there," McKinna said.

"Clark has plenty of experience and Matty can do a job there too."

Whatever way McKinna decides to go the Mariners will miss Heffernan.

After taking time to recover from a broken leg last season Heffernan has turned in several eye-catching performances this year.

Meanwhile, who plays alongside Matt Simon up front is still to be determined.

While Simon is a constant in attack when fit for the Mariners, his partner has changed regularly with Nik Mrdja, Adam Kwasnik and Ahmad Elrich all in contention.

The Mariners are under pressure to perform after back-to-back defeats against Gold Coast and Melbourne.