Williams hasn't played in the NRL since 2014 but is returning to the Sydney Roosters with his Canadian club Toronto Wolfpack pulling out of the Super League due to COVID-19.
Williams, who turns 35 next week, has told Nine News he had booked flights to go on a European family holiday before the Roosters came calling with their two to three month deal reportedly worth $150 thousand.
"Everyone knows it's no secret that I'm pretty close with the lads at the Roosters, Nick (chairman Nick Politis) and Trent (coach Trent Robinson) and I stay in contact with them now and then," Williams said.
"Trent just gave me a call and inquired about what was happening over here and Nick hit me up and asked if I had a couple of months in me to come back.
"To be honest, I hadn't trained for a bit and I'd been in holiday mode - we actually booked flights for a little family European holiday."
"It's the challenge that I just get so excited about - it lights that fire inside of you."
Williams and his family will need to spend two weeks in quarantine when they arrive in Sydney meaning Williams is unlikely to appear for the Roosters before round 15 towards the end of August.