Shellharbour coach Dave Walsh called for greater attention to detail from his side after Sunday's hot and cold performance against crosstown rivals Albion Park-Oak Flats at Ron Costello Oval.
The second-placed Sharks never looked like losing but the 42-16 victory wasn't impressive as the score might suggest.
"At half-time I was really happy with our defence," Walsh said.
"I was a bit disappointed we let them in for a few tries in the second half."
After failing to crack the Eagles in the opening 10 minutes, the home team suddenly exploded with a try to centre Bronx Goodwin and two to fullback Ian Catania. When Jamie Manukonga crossed out wide in the 25th minute, the lead was 20-0.
Sharks centre Ben Stratton blew a chance to inflate the margin when he dropped the ball over the line and the 20-point spread remained until half-time.
Shellharbour were on track for a cricket score when they added two tries in the first five minutes of the second half.
But they took their foot off the gas over the next 15 minutes, allowing the Park to post tries to Matt Carroll (two) and Kyle Zimmerman.
The Sharks still had the final say as prop Harold Snell barged over for his second try in the game's dying seconds.
"On the whole we tried a few things, but we probably got a bit complacent with the ball and probably forced a few errors," Walsh said. "We lost our way for a 15-minute period. It's something we have to talk about. We can't afford to drop off in any game.
"Defence is something we pride ourselves on, and they're filthy on themselves for letting it happen. There's certainly stuff we can work on."
The Sharks are looking forward to their upcoming clash with Nowra-Bomaderry.
"There's still a fair few games to go,'' he said.
''We've lost some key players to injury over the last few weeks, so we're starting to get a little bit stretched with our depth.
"We've got a tough game coming up against Nowra at Nowra. They've been a really good attacking team so we have to be at our best defensively."
Albion Park coach Shane Sainsbury said his team never quit.
"We competed in that first 10 then we fell away and slipped off too many tackles. We came back and competed in the second half.
"The boys are just learning the hard way but they're a lot better than the results show week in, week out," he said.
Meanwhile, Nowra-Bomaderry had a 32-12 road win over Kiama.