Sporting CP forward Bas Dost was injured by a group of men who gained access to the team's dressing room at their training centre.
Dost was one of several players assaulted as 50 hooded men also attacked physiotherapist Mario Monteiro and assistant Raul Jose, per O Jogo (h/t Lucas Sposito at Sport Witness).
Journalist Kristof Terreur showed the injuries suffered by Dost and indicated the men may have been Sporting supporters:
Manager Jorge Jesus and players William Carvalho and Rui Patricio were also reportedly involved, per A Bola (h/t Sposito).
Sport Witness shared images of the attackers:
Midfielders Josip Misic and Rodrigo Battaglia were also treated for their injuries, according to freelance football writer Rui Miguel Martins:
Football writer Marino Peixoto condemned the attackers' actions:
Trouble flared at Sporting in April when club president Bruno de Carvalho suspended 19 players after a spat on social media. De Carvalho said some of the team were "stupid" after losing 2-0 to Atletico Madrid in the UEFA Europa League, per the Guardian.
The players then released a statement in which they expressed their view and said the situation should be resolved internally.
“We always fight for our club, for our supporters and ourselves. For this reason, we express in this message our displeasure at the public comments of our president after a game in which we did not get the result we wanted. No matter what the situation, all such matters should be resolved within the group."
Jesus subsequently said that none of his players had been suspended or refused to train after the incident, per BBC Sport.
Sporting finished the season in third place in the table meaning they miss out on qualification for next season's UEFA Champions League.
The result brought fresh speculation that Jesus and his backroom staff had been suspended. This was subsequently denied by De Carvalho, per PT Football:
Jesus is still expected to leave the troubled club and could head to Saudi Arabian side Al Hilal, per Portuguese football writer Tom Kundert:
Meanwhile, Sporting players are trying to terminate their contracts with the club, per A Bola (h/t Sposito).
Dost's agent, Gunther Neauhaus, has said the situation is unacceptable, as shown by Sport Witness:
Sporting's season is not yet over as they are scheduled to play Aves in the Taca de Portugal final on Sunday. Dost, who has scored 34 goals for Sporting this season, has been ruled out of the game because of his injures, per Sposito:
The final is an excellent chance for the club to end the season with some silverware, but they head into the match without their top scorer and with the club in complete disarray.