The sister of Patrick Ekeng, who died after collapsing while playing for Dinamo Bucharest, claims he said he was "feeling very tired" before the game.
Cameroon's Ekeng, 26, fell to the floor in the 70th minute of the televised Romanian league match against Viitorul and was pronounced dead in hospital two hours later.
"He told his best friend he was not able to play," Monique Chantal, Ekeng's elder sister, told BBC Sport.
"He said he was very tired."
She added: "Patrick was very generous, a gentleman. It is very painful he is leaving behind a family - it is like a dream, a nightmare."
Celine Chemi, Ekeng's mother, said: "It is difficult to talk about my son at this moment, but I believe in God and submit to his will.
"If this is football and the life of professional players then this calls for reflection."
Fifpro, the world footballers' union, and its Romanian member union Afan, are concerned about the level of first-aid treatment available to Ekeng.
Afan said that after the death of Nigerian Henry Chinonso Ihelewere in a pre-season match in 2012, it asked the Romanian football federation to make it compulsory for clubs to have fully equipped ambulances at all official and friendly matches.
"It would have cost as little as 400 euros per club per match to have state-of-the-art equipment available but the plan was not adopted," said Afan president Emilian Hulubei.
"We are continually fighting for more rights for players. Footballers in Romania are a long way from being treated the way normal workers should be."
Fifpro general secretary Theo van Seggelen added: "Our thoughts go out to everyone affected. It's simply shocking.
"After local authorities complete their investigation, we expect answers as to whether or not this tragedy could have been avoided."
Dinamo Bucharest say they contracted three ambulances for the match and that they were "properly equipped for emergency interventions".
Team doctor Liviu Batineanu said: "The player collapsed on the ground. We went in immediately, without waiting for the referee's permission, and we began the first resuscitation manoeuvres."
Ekeng last spoke to his mother on Thursday before she left for a trip to a nearby village. She says he talked about the house he was building back home in Yaounde, the Cameroonian capital.
"We did [normally] speak every day," she said. "But because I was in the village he sent someone to see me and I was to call when I came back."
The club is making arrangements for the repatriation of the body.
The Romanian Football Federation announced on Saturday that the Romanian Cup final between Dinamo and Cluj would be put back a week to 17 May.
It said all games scheduled for this weekend would be postponed.