Doncaster Knights prop forward Ian Williams has died after collapsing in training, the Championship club confirmed on Tuesday.
The 27-year-old could not be resuscitated after collapsing during a training session at the club's Castle Park base.
A statement released by Doncaster read: "It is with great sadness that Doncaster RFC announces the passing of prop forward Ian Williams.
"Ian collapsed at training at Castle Park this morning and, despite the best efforts of the emergency response team, could not be resuscitated.
"Ian joined the Club in summer 2017 from Rotherham Titans and quickly became a well-liked member of the Knights squad making six appearances for the Club.
"We extend our deepest sympathies to Ian's mother Pippa, father Phillip & and sister Helen and are working with a counselling team in the best interest of Ian's teammates."
Williams' former club Rotherham led the tributes to the prop forward.
In a statement posted on Twitter, the club said: "@RotherhamRugby are deeply saddened to hear the tragic news that former prop forward Ian Williams has passed away. As a Club we pass on our deepest sympathies to Ian's family & close friends #RugbyFamily"