Australia’s National Rugby League was in shock Tuesday at the sudden death of promising Manly Warringah Sea Eagles rookie Keith Titmuss at the age of just 20.

The club said Titmuss “took ill” after training in Sydney on Monday morning and was taken to hospital but died a short time later.

“We are all devastated by this news,” Manly coach Des Hasler said in a statement late Monday.

“Keith was a very popular character amongst the playing group. He will be sorely missed but never forgotten by the Sea Eagles.”

The club did not give a cause of death for Titmuss, who had advanced through Manly’s junior ranks to become a full-time squad member on the brink of breaking into first grade.

NRL chief executive Andrew Abdo said the league was offering support to Titmuss’ family and teammates.

“This is a tragic day for rugby league,” he said.

“The game has lost a promising young player with the world at his feet.”

Former rugby league and union international Lote Tuqiri expressed shock.

“Losing kids in the prime of their lives is so hard to fathom . . . Fly high young man!” he tweeted.