Colombian striker Fredy Montero grabbed a goal in either half to take his tally to 13 league strikes in 12 games as Leonardo Jardim's side moved above rivals Porto and Benfica on Sunday.
Their challenge was made a little easier midway through the second half when Pecks was shown a straight red card, but Sporting were never troubled as they recorded a fourth consecutive victory to take an outright lead of the Portuguese top flight for the first time since January 2005.
The visitors controlled the game from the outset, but only edged ahead after Anthony Seric was dismissed for Olhanense in the 72nd minute. Ukra was Rio Ave's matchwinner as he netted his second league goal of the season with 11 minutes to play.
Sunday's other Primeira Liga fixture saw Nacional's winless run extended to five games as they were held to a 2-2 draw by Maritimo.
