The Roosters went ahead when they decided to run it on the last and teen sensation Latrell Mitchell dabbed it into the in-goal for Daniel Tupou's first of two tries.
Tupou bagged his double when ex-South Sydney premiership winner Keary put in an inch-perfect bomb for the Roosters' winger who soared above Brenko Lee as the home side took a 16-8 lead into halftime.
When Shaun Kenny-Dowall batted back for Ferguson, the Roosters' centre crossed for a try which almost mirrored Tupou's touchdown on the other side of halftime and the Roosters were threatening to run away with the game.
The Bulldogs' fightback began when Brett Morris muscled his way over three defenders, including Mitchell Pearce.Ferguson failed to finish the game after leaving the field with 19 minutes to go.
And when Bulldogs skipper James Graham sent Adam Elliott through a hole, the margin was just four with 16 minutes on the clock.
Both sides were left battered and bruised and it was Keary who stood up when it counted, throwing a no-look pass to send Mitchell Aubusson through a hole for the match-winner.
When Josh Morris scored his second with three minutes remaining, it sep up a grandstand finish but the Roosters held on.
The result heaps pressure on Dogs coach Des Hasler and marks the first time since 2010 that Canterbury have started the year with back-to-back losses.
Hopoate has been taken to hospital while Ferguson has been sent for scans on a rib cartilage injury.
The Bulldogs also have concerns over winger Kerrod Holland who suffered a shoulder injury scoring the opening try and is facing several weeks on the sidelines.
In the end, they were made to pay after losing Holland's goal-kicking, with fill-in Moses Mbye missing three attempts and Michael Gordon's boot proving decisive.
Roosters coach Trent Robinson said there was a lot to like about Keary's performance, however he was critical of his goalline defence which led to one try.
He was similarly excited for his side's second-up effort but emphasised there was a lot to work on."I thought we played really well but made lots of errors," Robinson said.
"Giving away a penalty or dropping a ball or a strip or diving on a loose ball.
"But I felt like we were right in the match but then there were lots of errors and that's why we're so far from home but we're on the right track."
Hasler praised his side's resilience, after they were at one point reduced to one man on the bench but still fought back.
"At the end of the day, we didn't get the points," Hasler said.
"I thought there were a couple of things that I'm not particularly pleased about - them getting three tries off kicks, little things like that, 40/20s - they hurt. Not catching the ball on the full, they come back and get you, don't they?"
- AAP
