A late try by replacement Gavin Quinnell saw the Llanelli Scarlets earn a place in next Saturday´s Celtic Cup final at Lansdowne Road. Quinnell, the youngest brother of former Wales and Lions number eight Scott, crossed the line in the 79th minute to clinch victory from League Champions The Ospreys at Stradey Park. The score put the Scarlets into the lead for the first time in the match and they will now face the winners of Sunday´s all-Irish semi-final between Munster and Leinster. Ospreys fly-half Matthew Jones had given his side a 12-0 lead early in the first half, but the second-half sin-binning of Wales lock Brent Cockbain proved crucial. The Ospreys took early advantage of a strong wind at their back with Jones slotting over two superb long-range penalties. He landed another after 12 minutes as the Ospreys began to control the game up front. The Scarlets fought their way back into the game as the half progressed, although they were struggling to break through a solid Ospreys defence. The match was an ill-tempered one and Scarlets lock Chris Wyatt was lucky not to see yellow for a late challenge on Jason Spice, although Jones punished the home side with his fourth penalty on 32 minutes. The Scarlets who had the final word of the half when Peel set up a score with a trademark tap-and-go. Veteran prop John Davies was the man on hand to pick up and gallop 15 yards for the score. Thomas´s conversion made it 12-7 at the break and the fly-half added a penalty two minutes after the restart to bring the scores even closer. The two fly-halves then swapped penalties as both sides continued to be penalised by Irish official Donal Courtney. A fine break by Thomas should have created a second try for the Scarlets, but Thomas ignored wing Garan Evans on his outside and the chance was missed. The turning point in the game came when Cockbain was awarded a yellow card after 63 minutes for an off-the-ball challenge, but Thomas missed a penalty from halfway. Replacement Gavin Quinnell then began to make his mark on the game. He first appeared to have scored from a short-range scrum, only to be ruled just short. However, there was no stopping him moments later as he crossed the line for a try his brother would have been proud of. Thomas´s conversion made it 20-15 and it was left to full-back Barry Davies to seal victory with an injury-time penalty.