"Vercauteren is no longer the coach of the main team. Jesualdo Ferreira will accumulate the roles of manager and head coach of Sporting's first team," the club told the Portuguese stock market regulator's website.
One of Portugal's 'Big Three', alongside Lisbon neighbours Benfica and the domineering Porto, Sporting are going through an acute crisis.
Ferreira, 66, won three championships as coach of Sporting's northern rivals Porto before spells at Spanish side Malaga and Panathinaikos in Greece.
Vercauteren, who had taken over at Sporting just three months ago, was unable to turn around a disgruntled Sporting side who endured their worst league start ever and languish 12th in the league, with only two wins in 13 matches.
Sporting have failed to win the league title since 2002 and have finished 16, 28 and 36 points behind the champions in the past three seasons.