Ospreys surged to the top of the GUINNESS PRO12 with a superb 31-20 home win over Ulster Rugby, Rhys Webb crossing twice for his tenth and eleventh tries of the season. Dan Biggar had also gone over for the hosts when Wales international Dan Lydiate was introduced with 49 minutes played to make his debut for the Swansea outfit. Ulster were much improved in the final 15 minutes as Rob Herring and Tommy Bowe went over, but Hanno Dirksen got the vital fourth try to seal the bonus point and send Ospreys to the GUINNESS PRO12 summit with their eighth consecutive league win at home. Bigger gave the hosts the lead on three minutes with a well-struck kick after Ulster needlessly conceded a penalty in the middle of the park. A lovely handling move from Ulster – with Ruan Pienaar, Louis Ludik and Bowe keeping the ball moving – then saw them move 50 metres up the pitch and gave Ian Humpreys the chance to make it 3-3 with a 15th minute penalty. But after Eli Walker did superbly chasing back to deny the visitors, he started a wonderful flowing move that allowed Biggar to go over for the game’s first try. Ospreys kept the ball off the ground with fast interplay, and after Alun Wyn Jones made the key break his offload to Marc Thomas put Biggar clear, the fly-half adding the extras himself. The home side’s flowing rugby was infectious, and Dirksen made two more big breaks down the right in quick succession, but Ospreys could not go the distance as Ulster defended desperately. Rory Best then prevented a certain try with a world-class last-ditch tackle on Dan Evans on the right flank, but could do nothing to stop another try of the highest standard by Ospreys on 37 minutes. Taking advantage of a strange decision by Humphreys to move the ball onto his weaker foot to clear, Ospreys built the pressure and Rynier Bernardo broke through to feed Webb who flew over. Biggar once again made the simple conversion and the 14-point lead reflected the first half dominance of the home side. Ulster looked for a response just before the interval, and Ludik was hit high allowing Humphreys to go for the corner. After a strong driving maul, a bizarre passage of play saw Humphreys go over to leave Ospreys incensed with referee Neil Paterson. But two visits to the TMO ensured the right decision was reached, and the try was disallowed with Ospreys ruled not to have had the advantage after two knock-ons in the buildup. Ulster won a penalty in front of the posts straight after the break, Humphreys kicking a desperately needed three points to make it 17-6. But Ospreys turned it on again, Josh Matavesi and Justin Tipuric with a couple of fast offloads to feed Eli Walker, and after the winger spilled the ball Webb was first to react to go over for his second of the evening. The flawless Biggar converted for his 15th straight successful kick in the GUINNESS PRO12, as Welsh international and British and Irish Lion Lydiate was introduced with 49 minutes played. Ospreys went for a fourth kicking for the corner, and sealed it with a fourth try when Dirksen went over from a five-metre scum on 55 minutes. Ulster at last got over the try-line with an impressive surge from the pack in the 60th minute allowing replacement Rob Herring to give them some hope. And Tommy Bowe then scored against his old side, cutting a perfect line from a lineout play to close the gap to 11 points with ten minutes left. But the home side tightened it up for the final stage of the game to seal only their second win over the Ulstermen in seven encounters, who remain without an away win since their visit to Cardiff Blues in September. Follow us on Facebook, join the conversation on Twitter, sign up to ourYouTube channel for extensive match highlights and sign up for ournewsletterfor regular updates on the GUINNESS PRO12