Impey, who rides for the Australian-based Mitchelton-Scott, feels unsure about his chances especially since he has no support system at his disposal.
“The road race will be a bit of a lottery for me,” he said. “I don’t really have any tactics heading into it.
“It’s going to be really difficult to pull off a win. There are a lot of top riders who have teammates to support them.
“I will be on my own and I don’t really have a plan for that. For me, it will be more about just racing clever on the day. I am not too sure what the other guys’ tactics will be either.
“I will just have to improvise and call the shots as the race goes on,” he added.
Impey, who won his seventh National time-trial on Wednesday, said quite a lot of “factors can play a part on race day”.
“You can be the strongest rider in the field. It still doesn’t mean you are going to win,” he said. “There are a lot of guys who could be targeting you.
“Teamwork also plays an important role,” he added.
His recent successes may play in his favour, Impey added. “Coming off a big win down under was massive,” he said. “It did gives me some momentum and surety of my form.
“I have also had an earlier pre-season than in previous years, so I am prepared.
“But going for the title I have got to put everything into it and have all my ducks in a row.”
The Dimension Data riders would pose the biggest threat, he said. “It will be foolish to underestimate them; they are a strong team.
Impey predicts a big bunch sprint finish. “The route is flat and there are no steep, long climbs or many technical sections.
“The competition could be stiff, so I think there is a good chance for a bunch sprint,” he said, “but that also depends on the wind.”