"It is hard to rate their form against ours but good Australian horses are always hard to beat over the shorter distances and then we have the fact the track is heavy and could still be by Saturday.
"He has won on a soft and is very nippy on his feet so I think he will handle heavy but you never know if he will handle it quite as well as those other top five or six chances. And then he might simply get a bit too far off them, so there are a lot of variables."
Aegon beat a very good filly in Amarelinha last start and did it without having raced for two months so it wouldn't surprise to see him win.
But Rosehill rarely suits New Zealand horses and he could impress yet still finish fourth or fifth. So while he is the $4 equal-favourite, he is hard to back with confidence with so many factors against him.
If he does win, his later Guineas targets in Sydney will look his to lose.
Aegon is half of a mega Kiwi double act across the Tasman with Probabeel second favourite for the A$500,000 Futurity Stakes at Caulfield in Melbourne.
She steps up in grade to Group 1 weight-for-age after destroying a mares field last start but is awkwardly drawn so she will need to be the real deal to win again, with her main aim, the A$5 million All Star Mile, still three weeks away.
With cracks starting to appear in the Victorian weight-for-age ranks, she is firming in the markets for all her main goals.
But she will still have to overcome Behemoth, Streets Of Avalon, Ole Kirk and the dynamic Western Australia mare Arcadia Queen.
Although Forsman doesn't know quite how to rate Aegon's winning chances in Sydney, he already knows the big names he trains with Murray Baker face huge tasks at Ellerslie.
The stable has Star Tsar and Robusto in the Avondale Cup and they have drawn alongside each other right on the outside.
"The draws make it hard — they will have to roll forward a bit and try and get in but it has become a very tricky race for them," says Forsman.
"But at least there is a long run from the 2400m to the bend so that might help."
Another wide draw dogs Frontman (R9, No 3) in the last race but it could be even worse as the 2100m start point has a much shorter run to the first bend so he will need plenty of Opie Bosson magic to overcome it.
"The Derby is still his target if he can win or go very well here but his draw makes it tough," says Forsman.
Most of the other New Zealand Derby contenders on show contest the $120,000 Avondale Guineas.
But the big question around the Derby will come in the next few days when the connections of flying fillies Amarelinha and Tokorangi decide whether they target the March 6 classic at Ellerslie.
Saturday's big races
4pm: $120,000 Avondale Guineas, Ellerslie.
4.35pm: $100,000 Avondale Cup, Ellerslie.
5.35pm: A$500,000 Futurity Stakes, Caulfield.
6.35pm: A$400,000 Hobartville Stakes, Rosehill.