Former Queens Park Rangers midfielder Joey Barton shadowed the Wigan Warriors coaching staff on Thursday night during their Super League game against Leeds Rhinos.
The 32-year-old, who spoke to the coaches and players, was allowed in the dressing room before and after Wigan's 26-24 victory at the DW Stadium.
"He came in before the game and was blown away by the level of detail we go into," PA quotes Wigan coach Shaun Wane as saying. "It was pretty mind-blowing for him.
"He watched the documentary of us in Australia and spoke about that. He's a big rugby league fan. He knew everybody - when the players went up to him, he knew more about them than they knew about him."
Barton is currently a free agent after being released by QPR in June.