Hardaker broke into the Rhinos team at centre but was at full-back in the last Exiles clash at Huddersfield last July and has since worn the number one jersey with distinction for the Super League champions. However, Sam Tomkins has reclaimed the full-back role for England and Hardaker will be switched by coach Steve McNamara to centre following the loss of Watkins with an ankle injury.
"I wasn't really expecting to get picked so I'm pretty excited," Hardaker said from the England camp at Loughborough University.
"It's a new position for me again. I played a bit of centre for Leeds so it's not totally new to me. I've played in a Grand Final at centre and I've been looking at a few videos and a few things I did last time.
"Kallum has been going really well and I'll try to do him justice but they are pretty big boots to fill. I told Steve I will play anywhere for my country. It doesn't really matter what position I play, I'll still give it my all."
McNamara has yet to finalise his line-up but his three-quarter line virtually picks itself and Hardaker is looking forward to linking up with his Leeds team-mate Ryan Hall, England's deadly finishing winger, at the Halliwell Jones Stadium.
"Leroy (Cudjoe) plays on the right for Huddersfield so I'll be playing on the left with Hally which should be good," Hardaker said.
"I've played with Ryan before. I'll just pass him the ball, he can finish most tries off. If he can't dance around them, he'll probably go right through them."
Friday's one-off game with the cream of Super League's overseas players will be England's last competitive outing before the World Cup and Hardaker is expecting a stern test of their credentials.
"We're looking at this game in its own right," he said. "Obviously the World Cup at the end of the year is massive but we really want to do a job on the Exiles."