Coach Graham Arnold has a clutch of options to weigh up for the Central Coast Mariners' vacant striker berth after Matt Simon's grand sign-off.South Korea-bound Simon highlighted the size of the gap he's leaving at the A-League ladder leaders when he farewelled the club by scoring both goals in Wednesday's 2-0 win over Melbourne Victory.But Arnold is not short of choices to replace him, starting with Sunday's away clash with Sydney FC.Adam Kwasnik and Daniel McBreen both have lots of experience playing up front, while youth league players Mitchell Duke and Kwabena Appiah Kubi are highly regarded.Highlighting the Mariners' depth, Arnold could also choose to play versatile Troy Hearfield up front in partnership with the electric Bernie Ibini.The 24-year-old Hearfield, a former Wellington Phoenix and Newcastle Jets player, has mainly been used as an impact player off the bench this season.But he has impressed with some stellar performances in recent weeks and was rewarded with his first start of the season against the Victory in his 100th A-League appearance."Graham Arnold has shown a lot of faith in me, and it was great to get my first start for the club," said Hearfield."It was fantastic for Matty Simon to go out like that. He couldn't have asked for anything more."Hearfield and Simon struck up a promising combination when they had the opportunity to play together, assisting each other to important goals through the Mariners' current unbeaten streak."It's been great to play with Matty but now he is gone and, as a team, we will have to adjust."Bernie is great young player and the challenge is to try and get a partnership with someone else in the team."Hearfield believes the culture and close friendship at the Mariners has been a key factor in achieving their lofty position on the ladder."It's a tight-knit group and a positive environment which starts from the top," said Hearfield. "Graham Arnold and the coaching staff know what they want from the team."