Leinster have "another 10%" that they need to find quickly, according to senior coach Stuart Lancaster.
The reigning Pro14 champions suffered a 23-21 defeat to the Scarlets in Llanelli on Saturday evening.
It was the first time the two sides had met since Scarlets lost to Leinster in last season's grand final, and though the visitors included Ireland internationals Robbie Henshaw, Jordon Larmour, Cian Healy, Sean Cronin, Tadhg Furlong and Devin Toner, early-season ring-rust was apparent.
"We played a good team away from home so it was always going to be difficult but we were disappointed to lose," said Lancaster on Monday.
"We put ourselves in a position at half-time where we were 14-10. To then go 13 unanswered point and allow their belief and momentum to grow, which left us chasing the game in the last five minutes...
"There's plenty to work on and there's certainly no room for complacency. We had a tough review this morning."
It was the second away game on the bounce for Leinster, who opened with a dramatic 33-32 win at Cardiff Blues.
Having won a historic Champions Cup and Pro14 double last term, Lancaster accepts they're the team everyone else wants to beat and, although their internationals are still getting back up to speed, he's not leaning on any excuses.
"It is difficult," Lancaster added as he looked ahead to this weekend's RDS clash with the Dragons.
"You've got a lot of Ireland players who played a significant part of last season all the way through to the last Test on 26 June.
"Clearly they're not going to start the season like other players would. It makes it a challenge to reintegrate the players on a weekly basis, getting everyone up to speed, cohesion in your game plan and also making sure they hit top form for the first game of the season.
"There are challenges but that said we've been together long enough now to put together really good performances from the start. There's another 10% in us that we need to find this weekend."
