Dave Furner was surprisingly sacked by the eight-times Super League champions yesterday just six months into a three-year deal with the club having won only four of their opening 14 games.
Marshall - whose exit from Halifax a fortnight ago was a similar shock - has emerged as a joint-favourite to take over at Emerald Headingley.
Ex-Wigan boss Shaun Wane and interim Rhinos coach Richard Agar - the former Wakefield Trinity, Hull FC and France chief - as well as Marshall are all priced at 5/1 by Betfred.
The 43-year-old had earned praise as one of the sport’s most promising coaches after taking part-timers Halifax to three top-four finishes in his four seasons at The Shay as well as developing a raft of homegrown talent.
Marshall has worked in Super League before having been an assistant to Tony Smith at Warrington Wolves where Grix was also under his wing before following him to Halifax.
Asked if he thought his former coach was ready to step up to such a big role, Grix said: “Yes, why not?
“The bookies say he is in the frame don’t they?
“Richard did well at Halifax and it’s whether Leeds will be brave enough to take on someone who would be a novice as a Super League head coach.
“I was with him yesterday (Tuesday) and he’d not had any contact from them so it might be people putting two and two together and getting five.
“But you never know - that call might come today.
“Richard has been an assistant in Super League and he is so hard-working, always looking to improve and I don’t see him being out of work for long.”