Doncaster Knights centre Will Owen has paid tribute to team-mate Ian Williams, saying the prop's "charm and kindness were contagious".
Williams died on Tuesday aged 27 after collapsing during training and could not be resuscitated. His cause of death is not yet known.
"He is honestly one of the best people I have had the pleasure of knowing," said Owen, 24, who captained Williams at Rotherham last season.
"I'm proud to call him my friend."
"He was a popular member of the squad and was always in the middle of any kind of social gathering," he added. "His charm and kindness were contagious."
Owen said that after Williams collapsed on Tuesday, the Championship club sent the players home, with many choosing to stay together.
"He loved a glass of red wine, so some of us headed to the pub after we heard the news to toast his life," added Owen.
"It was just a regular training session and we split off into backs and forwards units as normal.
"I understand he collapsed while everyone was stationary and discussing a training drill.
"Our hooker Ben Hunter and our forward's coach Glen Kenworthy were among those on the scene who reacted brilliantly and were fantastic until the ambulance arrived."
Doncaster have cancelled their scheduled training sessions for the remainder of the week but the players are due to meet on Thursday for a team meal, says Owen.
Their next game is at Cornish Pirates on 4 March.