Leo Cullen admitted Leinster lost their way for a spell during the eight-try win over Scarlets at the RDS.
The 54-5 win saw Leinster move top for the first time this season but after a fast start that included three tries, the hosts stood still and went 34 minutes before getting their fourth try.
Leinster started with 10 of Ireland's World Cup players, with another three on the bench but Scarlets got on the board and had the upper hand in the second quarter.
"Maybe there is a little bit of flatness but we came very close to scoring a fourth try straight away when it was 19-0 and that was in the first 20 minutes of the game, and then we get a little bit loose for a period," Cullen (below) told RTÉ Sport.
"That's sometimes the way the game goes when you've got to turn your attention to defending your own line.
"We did that okay but as you expect, with a lot of guys coming back in there's a little bit of rustiness there because we haven't played together in a hell of a long time. Some guys were saying they haven't played at the RDS in a really long time, since last year, 2022, against Gloucester.
"Overall, we are pleased to get a win, I know Scarlets were a little bit depleted as well but our guys have come through the game relatively unscathed and I think that's the main thing. We got a win, got five points."
Sam Prendergast, Jimmy O'Brien, Max Deegan (2), Garry Ringrose, Jamie Osborne (2) and Jack Boyle all scored tries with Prendergast adding two conversions and replacement Ross Byrne four.
"It didn't really feel like a 54-5 [game]," added Cullen, whose side got the bonus point in the 50th minute when Ringrose crossed.
"We started well, good intensity, good mindset. After that we just lose our way to an extent. A lot of credit to Scarlets, they battled away, came up with some good turnovers at the ruck.
"We gave away a couple of cheap penalties and suddenly they are pinning us into the corner, they get over for a try and had some other chances as well.
"We did show some good defensive actions as well.
"We managed to hold them out until half-time and at the start of the second half it was probably a little bit similar until we get that breakout and Garry scores. I thought all our bench made pretty good impacts."
Leinster top the table on 20 points, ahead of Glasgow on points difference ahead of next week's clash with Munster at the Aviva Stadium (Saturday, 6.30pm).
"It's going to be a great challenge, they are amazing games," said Cullen of the rematch of last season's semi-final, which Munster won.
"That's what supporters want to see, they want to see two teams fighting for their jerseys and I think you'll get that."
