Griffin felt his five-eighth James Maloney was obstructed by Will Hopoate in the lead-up to the try, but on-field referee Adam Gee's referral upstairs came back positive for Canterbury, who built on their fast start to notch a first win for new coach Dean Pay before 11,247 fans at ANZ Stadium.

Barely five minutes after the incident, Cleary injured his left knee, and while he played out the first half, medical staff refused to let him back on after the break. The 20-year-old will undergo a scan on Saturday to determine the extent of the damage, but early indications suggest he's suffered a medial-ligament tear which could sideline him for multiple weeks.

"Obstruction," Griffin replied gruffly when quizzed on his thoughts on the Bulldogs' first try.

"I'm not whingeing about the result but that's why they brought the obstruction rule in, so that if a lead runner hit the inside shoulder of Maloney like that it didn't give him a chance to get out and they scored in the same hole. I thought it was just a classic obstruction.

"If we've got to take a dive [to win a penalty] that's not good for the game. It's not something we want to encourage our players to do but if you've got to take a dive to save a try, that's what they're encouraging you to do if they let tries like that in."

Maloney was equally bemused by the bunker's decision to award the try.

"I don't really know, I thought if you ran outside shoulder of someone you couldn't then come back inside and go through that hole, I guess that's not the case," Maloney said.

In a week where so much focus has been on the heftier penalty counts creeping into the NRL, it was again the referees in focus on Friday.

Five minutes into the clash, Bulldogs halfback Kieran Foran swung a ball out to Jeremy Marshall-King behind captain Josh Jackson and Hopoate, before the latter came into contact with Maloney's outside shoulder.

Marshall-King popped a short ball out to the brilliant Mbye who stepped through Maloney and Dean Whare to open the scoring.

It gave the Bulldogs a platform to build their first win of the year, and it was Mbye doing all the damage. He scored another later in the half and played a huge role in garnering field position for Hopoate's four-pointer, which propelled Canterbury to a 14-0 lead.

For the third time in three weeks to start the season Penrith were down 14-0 and requiring a comeback.

They eroded the gap to eight points by the half but were under-manned when Cleary didn't emerge, spending the second stanza on the sideline wearing a polo shirt with a chunky ice pack strapped to his injured knee.

Maloney shifted into halfback while Tyrone Peachey came off the bench to slot in at five-eighth as Penrith besieged the Bulldogs' defensive line, which just about held firm.

Josh Mansour's acrobatic effort in the 73rd minute bridged the gap to two points, but the Bulldogs hung on to hand Pay a much-needed win.

"It's a pleasing win that's for sure, we worked really hard during the week, we had a seven-day turnaround so the boys trained with a lot of intensity," Pay said.

"We tried to fix up a few areas, obviously our defence was a little bit better tonight.

"We had a fair few blokes out on their feet, they just kept turning up for one another. They're a really good group of boys, they stick together and that really shone through.

"There's a few of them that copped a bit of flak over the first couple of weeks for their performances. We just wanted to put a performance out there that we were happy with and the boys did that."

Griffin was hopeful Cleary's knee isn't wouldn't prove to be too serious.

"They checked him on the field and it wasn't too bad, when they came in at half-time and it cooled down and had another look at him and they pulled him, the doctor came and told me he was gone."