Porto were denied the chance to go three points clear at the top of the Liga ZON Sagres standings after conceding a late equaliser at Pacos Ferreira. Porto looked set to take full advantage of title rivals Benfica\'s draw at Olhanense on Friday night as they still led by Ricardo\'s 47th-minute own goal heading into the closing stages today. However, Lorenzo Melgarejo equalised for the hosts 11 minutes from time as Porto had to settle for just a one-point lead at the summit. Elsewhere, two Claudemir penalties helped Nacional beat third-bottom Beira Mar 3-0, with Ladji Keita adding a third goal 15 minutes from time. In today\'s other two matches Guimaraes beat Rio Ave 1-0 thanks to a 77th-minute Edgar goal, while Vitoria Setubal were winners by the same scoreline against second-bottom Uniao Leiria, with Miguelito\'s third-minute effort earning his side the points.