"Teams start getting desperate and pushing to be playing in September so you have to be playing your best footy at some stage and we want it sooner rather than later."
After the Warriors racked up a 12-0 lead in the first 12 minutes against Penrith, the visitors fought back to post three tries before halftime, and it took a Shaun Johnson intercept in the 71st minute to get the Warriors home.
It was a similar story the week before against Brisbane, when the Warriors carried a 13-6 advantage into the second half before a Ben Barba try on the hour put them back within three. This time it was Ngani Laumape's line-break that set up Chad Townsend's match-winning score with 14 minutes left to play.
Mannering wants his side to be more clinical after establishing leads, and says it's just a matter of not getting too far ahead of themselves and sticking to their gameplan.
"There were a couple of areas to get better at after the Penrith game and hopefully we can get those things right. Just the simple things, from that last game - we'd put ourselves in a pretty good position early on and then gave the opposition a fair sniff through decisions made by us. It's just a matter of sticking with the processes of our gameplan and generally if we do that we have a bit of success."
Coach Andrew McFadden agreed and revealed much of their focus this week had been on improving their execution in attack and defence.
"Execution in both areas of our game is the main focus at the moment. Certainly bringing a better level of intent in our defensive game and our offensive game has been a big focus," he said.
McFadden is wary of the slippery Eels, a team he rates as being among the NRL's most unpredictable attacking outfits.
"They've got some guys in their side that can play off-the-cuff football," he said. "They're very hard to handle so we're going to have to be working very hard defensively to stop that. Their whole side caused us a few problems early in the season.
"I think our game has changed since then so I'd expect we're going to put in a better showing this week."