Ospreys, inspired by James Hook, moved within five points of Celtic League leaders Leinster following a 19-6 win over Llanelli at Stradey Park last night.
A bonus-point win against Leinster at the Liberty Stadium on Friday would see the Ospreys draw level with the league leaders - crucially, Ospreys also have a game in hand.
Shane Williams broke from his own 22 in the second half to ease Ospreys clear, Hook supporting for the key try and adding 14 points with kicks.
Stephen Jones's two first-half penalties were the only scores for the Scarlets.
Northampton forward Dylan Hartley's career is in ruins after he was hit with a 26-week ban by Rugby Football Union disciplinary chiefs.
The highly rated Saints hooker was found guilty of illegally making contact with the eyes or eye areas of Wasps forwards James Haskell and Jonny O'Connor during a Guinness Premiership game nine days ago. He also faced an identical third charge involving Wasps' England star Joe Worsley, but was found not guilty on that count.
He will not play again until October 17.
The 21-year-old had been a strong contender for England's tour of South Africa, which begins next month, and the 2007 World Cup campaign in France.
But those hopes have now been destroyed by the suspension imposed by a three-man panel sitting in London.
Hartley was cited by an independent match commissioner following the Premiership clash at Adams Park, which relegation-haunted Northampton lost 35-29.
It is believed to be the longest suspension dished out to a top-flight England player since the Bath prop Kevin Yates received a six-month ban after being found guilty of ear-biting in 1998.
Scrummaging coach Phil Keith-Roach - a key member of England's 2003 World Cup support staff - will end his full-time role with the Rugby Football Union next week.
London Irish and England captain Mike Catt leads the nominations for the English Professional Rugby Players' Association player-of-the-year award.
Catt (35) has been voted onto the five-man short-list for the second season running and is joined by Bristol loose forwards Dan Ward-Smith and Roy Winters. Leicester's Samoan winger Alesana Tuilagi and Saracens outhalf Glen Jackson, the Premiership's leading points scorer, complete the nominees.