Ulster and Cardiff Blues maintained their 100 per cent record at the start of the Pro12 campaign with narrow victories on Friday.
Both sides have now won all three of their opening matches of the 2016-17 season, with Ulster occupying top spot thanks to a better points difference.
Les Kiss' side edged a nervy encounter with Scarlets at the Kingspan Stadium, Ulster running in two tries to complete a 19-8 victory.
Two Paddy Jackson penalties and a Louis Ludik try gave the hosts an 11-0 lead at the break and, although Scarlets improved after the restart, Ulster had enough to hang on.
The boot of Gareth Anscombe ensured Cardiff remain on par with Ulster as he racked up 10 points in their 23-19 win over Glasgow Warriors.
Fly-half Anscombe kicked two penalties and two conversions in the first half as Cardiff took a 20-14 lead into the break, a quiet second half ensuring they remain unbeaten this season.
Leinster were also victorious on Friday with a 33-20 win over Edinburgh at Murrayfield, the latter suffering their second defeat in the early stages of the campaign.
A stunning first half from Leinster saw Dan Leavy, Garry Ringrose, Isa Nacewa and Jamison Gibson-Park all crossing the whitewash, Nacewa kicking three conversions to give his side a 26-8 lead.
Edinburgh mounted something of a comeback in the second half but Leavy's second try of the game late on settled any Leinster nerves.