The sensational pacer has drifted from $1.70 to $2.70 in the market since drawing wide on Monday and may not even start favourite tonight.
Purdon thinks that is fair, even as good and potentially great Self Assured may prove to be.
"It is very, very hard to win those big miles at Menangle from out there," says Purdon.
"We have had some really good horses, even Lazarus, draw wide in miles at Menangle and struggle and while I am not saying he can't win, he may have to rise to the next level to do so."
The big shorterner in the Chariots has been Victorian pacer Lochinvar Art, who was able to easily beat Self Assured when he led with the latter parked in the Bonanza at Melton last month. Purdon sees the same challenge unfolding tonight.
"He was very good when he beat us Lonchivar Art and I think he is the horse to beat again, he should probably even be favourite," Purdon says of the second elect.
"I think he will go somewhere between 1:48 and 1:50 for the mile and there are plenty of others on the speed who can do that too.
"So we are really up against it."
With the expected speed map and wave of money that will come for Lochinvar Art tonight, it wouldn't surprise to see him replace the Kiwi pacer as favourite by race start time but Max Delight, Demon Delight and Hurricane Harley are other big chances in what should be a beauty.
Purdon faces a similar wide draw with Our Princess Tiffany in the Robin Dundee tonight, the final qualifying race for next week's Ladyship Mile.
A stunning winner of the NSW Oaks last season, Our Princess Tiffany has sometimes taken punters on a roller-coaster ride since, with another low when she failed badly at Addington last Friday.
"Something wasn't right with her then but she seems to have travelled over well and while she is drawn wide there looks to be a lot of early speed in he race so it may not be the negative for her it might be for Self Assured."
That mile race also contains Havtime, who has a better draw than last week at one, northern mare Step Up and Canterbury speedster Bettors Heart, all four needing to run at least top four to be guaranteed a spot in next Saturday's Ladyship.
New Zealand fillies Dr Susan and Stylish Memphis are expected to win their heats of the NSW Oaks tonight heading into next week's final.
Chariots on fire
●Auckland Cup winner Self Assured is favourite for tonight's A$200,000 Chariots Of Fire at Menangle.
●His trainer-driver Mark Purdon is very worried by the outside of the front line draw.
●There are a number of strong Kiwi chances at tonight's first night of the Miracle Mile carnival.
