Kelly has been out for ten months with a serious knee injury.
"It was great to have Lucas around to talk to. When I'd say my tendon was aching he would reassure me that was normal," he told the Liverpool Echo.
"He was a big support but his rehab was different to mine. His cruciate was done by a tackle; mine was done by being off balance. He was back within six months but my rehab took longer because I'm a different type of player to Lucas."