Evan Hawksworth, who plays for Stanley Rovers U14s’ team, sustained a head injury during a game on Sunday.
He underwent surgery to stop a bleed on his brain.
Both Wakefield Trinity and Super League leaders Castleford Tigers have offered their support by taking to Twitter.
Trinity said: “All players & staff here at Wakefield Trinity have Evan from @StanleyU14s2017 in our thoughts & prayers! Keep fighting young man.”
Shortly afterwards, Tigers said: “All our thoughts are with Evan Hawksworth right now. Keep fighting Evan, our whole team are right behind you! #RLFamily”
On Sunday evening a Facebook post by Stanley Rovers U14s coach, Steve Abraham, read: “Evan Hawksworth is one of the nicest 14-year-old lads I have ever met and has a heart of a lion.
“The next 24 hours are critical for the lad so please can all of my friends on here and rugby family in general say a prayer for Evan and his family it would be appreciated.”