Leinster bounced back from a draw with Benetton Treviso on Saturday by beating fellow GUINNESS PRO12 title contenders Ospreys 18-12 at the RDS Arena.
The Irish province had the boot of Jimmy Gopperth to thank after two late penalties handed them the win, but it was another scrappy performance from the three-time European champions where they did not cross the try-line once.
And ahead of a trip to the Twickenham Stoop for the first Harlequins clash, full-back Kearney insists his side needs to lift their level back to where it belongs.
"We lost the second game of our double-header with Northampton last year and that pretty much defined our season," the 25-year-old told the Irish Independent.
"We had to go to Toulon for a tough quarter-final where we lost. I think these two weeks are going to be massive for us in defining the rest of our season.
"We know we need a big performance. The last couple of weeks haven't been the normal performances we would have liked. Last week wasn't particularly good to watch.
"If we perform like that again this week we will probably struggle."
Kearney will be hoping to edge his way into Matt O'Connor's side against Quins, with two GUINNESS PRO12 games under his belt since returning from the anterior cruciate ligament injury he sustained in last season's semi-final defeat to Ulster.
He added: "It happens so many times to players coming in where someone is injured and it gives opportunity to someone else to perform.
"The fact that a couple of lads were on international duty was good for me in terms of getting game time, coming straight back into it.
"I would like to think that some of the performances last year would have helped as well with the coaches, but in the bigger picture you are back to the bottom of the barrel and need to fight and get your back place back."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland