Leinster missed the opportunity to go top of the Guinness Pro12 after they were beaten 23-13 at strugglers Newport Gwent Dragons.
Jason Tovey scored 18 points as the Dragons secured a richly-deserved fourth league win of the campaign. The fly-half went through the card with a try, two penalties, a drop goal and two conversions, while wing Ashton Hewitt got their other try.
Leinster's Fergus McFadden booted two penalties and converted scrum-half Luke McGrath's try but the Irish side failed to leapfrog Scarlets at the top of the table.
Leinster lead for 20 minutes of the first half but the Dragons could easily have grabbed a try bonus point in that space of time given the pressure they had on the visitors.
As it was, in the driving rain, the Welsh region went in 17-10 ahead after Hewitt, who had a storming opening period, put the Dragons ahead after he dashed past McFadden and prop Michael Bent to the line.
Leinster came out fighting after the interval and McFadden secured his second penalty of the night from 25 metres. The visitors mirrored the home side's pressure in the right-hand corner of the pitch and came within inches of a second try but the Dragons defence kept them out and cleared their lines.
And, when Leinster put their hands in a ruck, Tovey booted his first penalty to restore the seven-point advantage. The Irishmen were dealt a blow when McFadden was sin-binned with nine minutes left for a dangerous tackle on Sarel Pretorius when he was on the ground.
That sank Leinster and a final Tovey penalty denied the Irishmen a losing bonus point.