Gers remain unbeaten this season as they bid for a Scottish Premiership title push under the Scouse legend, and Johnson is relishing the prospect of testing himself against one of Glasgow's big two at Fir Park.
"Rangers is a tough challenge," said the 25-year-old former Gateshead striker.
"We will have to dig deep and try and get a result.
"It is a big test. It is one of the reasons I have come up here, to play against Rangers and Celtic and test myself against better players than I am used to.
"Scottish football is a step up from where I have come from.
“There is so much more tactical stuff we do during the week.
“The passing and the tempo is so much quicker.
“You can switch off in the National League but here you need to be switched on all the time.
“Motherwell got to two cup finals last season and we want to do it again. This is why I have come to the club.
"It is a club that is growing.
"I want to be the next English striker who comes up here, does well and scores the goals."