Sullivan was instrumental in shooting the green and golds to a 25-0 first half lead - scoring one try, setting up two others and kicking a field goal - and looked to forge CYMS ahead further immediately after halftime when he chipped ahead and then attempted a second kick in pursuit of the bouncing ball.

But, in doing so, the awkward extension of his right leg tangle with a Hawks defender.

The former NRL gun came from the field immediately and didn't return.

Veteran five-eighth Matt Rose also limped from the field with a hamstring issue, but his isn't expected to be as severe as Sullivans.

The early departure of both halves caused some grief to the attacking continuity the Wade Park crowd saw early on, but CYMS proved too strong through the middle of the field with second half tries to Logan Polkington, Riley Law and Tim Mortimer enough to record a comfortable derby win.

"You lose a bit when your pivots go but the boys stuck it out and ended up with a convincing win," Sullivan said after the game, referee Jason Whitney also succumbing to injury in the first half.

"I won't know (the severity of the injury) until (Monday), but it's where I've had my graft before so it's a problem area, unfortunately.

"I've had a great off season and felt really good, it was great to be out there this early in the Group 10 season ... we've got the bye next which is the only saving grace."

Both sides had early chances to post the match's first points, but defence was what presented the green and golds with the best shot.

Too big, too strong up front against a Hawks side minus Arty Shead, CYMS muscled up on the two blues as they worked the ball out of their own end, and earning the football in good field position provided Sullivan with enough of an opportunity to work his magic, a deft grubber kick finding Sam Hill for the season's first four pointer.

McAlpine duly slotted the conversion and CYMS were up 6-0.

VIDEO: What Mick Sullivan and Jared Brodrick had to say:

It was an advantage they never let slip either.

Sullivan scored himself 10 minutes later, slicing through from close range to score under the posts, and then a Tim Mortimer off-load put Kyran Bubb in space to score the game's third try.

Five minutes before halftime, Sullivan was at it again, putting his brother Scott over down the short side before potting a field goal out of nothing inside the final 60 seconds of the first period to gift the green and golds a 25-0 lead.

That was as good as the game got though.

Sullivan limped off immediately after the break and Hawks hit back somewhat with tries to Glen Maxwell and then Tory Madden, but the result was never really in doubt, not after such an impressive first half from CYMS.

Further four-pointers to Polkington, Law and then Tim Mortimer - as well as the perfect boot of McAlpine, kicking seven from seven - sealed the win and enough for-and-against points to sit CYMS on top of the ladder after round one.

Sullivan was pleased with CYMS' ability to withstand early pressure, and then turn defence into points.

"I think derbies, it's always pretty tight in that first 10, 15 minutes but the most pleasing thing for me is we scored back-to-back tries ... we didn't give points or concede points," he said.

"We put back-to-back points on and that's the key to being a consistent side."

New recruits Simon Osborne and Polkington were great for CYMS up front, the former's ability to stand and offload in the tackle a constant headache for Hawks' defence.

While Cam Jones, too, was strong up front.

"The local kids we've already got, Cam, Bubby, Riley leading the way and Hilly was back to good form ... it's pleasing signs," Sullivan added.

He said with a bye next week and then road games against Lithgow, Oberon and Bathurst Panthers, a first-up win over Hawks was needed.

"It usually suits us to play away early," he said.

"I think it's good to freshen up with a run of home games leading into the end of the year, but I'm pretty pleased (today)."

ORANGE CYMS 43 (Sam Hill, Mick Sullivan, Scott Sullivan, Kyran Bubb, Logan Polkington, Tim Mortimer, Riley Law tries; Ben McAlpine 7 goals; Mick Sullivan field goal) def ORANGE HAWKS 10 (Tory Madden, Glen Maxwell tries; Cody Robbins goal)