Set by Les Brennan in 1954, Johnston has equalled his 29 tries in a season – the most of any NRL player this year.
Johnston said try-scoring had become similar to “riding a bike” for him, but the 26-year-old is still looking for ways to improve his skills.
“I want all the tries just to be me catching the ball putting it down, easy as that and I hope it can be like that this week,” he said.
“I’ve blown a couple of tries the last couple of years, so I’ve still definitely got things to work on.”