According to L’Equipe, negotiations between Lyon, Fonseca and Sporting are advanced, with the French club expected to receive approximately €5 million in compensation while removing his substantial salary from their wage bill.
Fonseca reportedly informed his players of his impending departure on Monday, having appeared emotional during Sunday's victory over Angers.
Lyon have considered several alternatives, including former Juventus boss Thiago Motta and Crystal Palace manager Pierre Sage, although the latter's return has been ruled out.
Vicens, who previously worked under Pep Guardiola at Manchester City, has been holding discussions with Lyon.
The Spaniard has been unemployed since leaving Braga in October, with any appointment unlikely before the international break.