Aled Thomas (with ball) secured a famous win for the Scarlets in Cork
The Scarlets' 13-6 away win to Munster was the highlight of what was a successful weekend for the Welsh regions in the RaboDirect PRO12.
Three of the four regions came out on top in their respective games with the Blues and the Dragons also securing wins.
The Ospreys were the only team to lose as a young side was narrowly beaten by Edinburgh.
With a number of players unavailable due to international fixtures and injuries, the last few weeks have seen the regional coaches give youth its chance. A lack of experience did not seem to matter for the Scarlets though as they claimed a famous win in what were appalling conditions in Cork.
With the rain and wind against them in the first half, Simon Easterby's side repelled wave after wave of Munster attack and Aled Thomas exchanged penalties with Ian Keatley as the sides went in level at the break.
Thomas added a second penalty after half time before Andrew Fenby's decisive score secured a historic win for the Welsh side. The win sees the Scarlets in second place ahead of a clash with league leaders Ulster at Parc y Scarlets next Sunday.
In Italy, Cardiff Blues got back to winning ways with a 7-14 win over bottom club Zebre. A try from prop Nathan Trevett and three penalties from the boot of fly-half Ceri Sweeney were enough to secure a win for Phil Davies' side.
The victory at the Stadio XXV Aprile sees the Blues move into ninth, one place and four points behind the Ospreys.
Despite defeat to Edinburgh at Murrayfield, a young Ospreys side showed the depth of talent available in the region with Matthew Morgan impressing at outside half.
Morgan scored all of the points for Steve Tandy's men including a try, a conversion and two penalties as his side raced into a 13-8 half time lead.
Sadly for the Ospreys youngsters, they were unable to hold on as the boot of Greg Hunter and WP Nel's try saw Edinburgh turn the tables.
In another fiercely competitive game at Rodney Parade, a Pat Leach try saw the Dragons secure their first PRO12 win since September.
Full back Tom Prydie kicked added three penalties as his side saw off Connacht for a much needed win.