Better still, his win at Te Rapa two starts back and in the Dunstan Stayers Championship at Ellerslie last start were both achieved in the wet - conditions he hates.
"I really don't know how he managed to win at Te Rapa," said Richardson. "I let him go around only because I needed a couple of points to make sure he got into the Dunstan final.
"I told the stipes that before the race. I told them I didn't think he was a chance."
When he got to Ellerslie, Green Supreme slaughtered the in-form Dunstan field, despite the slow track surface, prompting the question of how good he can get when conditions suit.
Very good and certainly good enough to beat this field.
But his place in the handicap underlines the current dreadful lack of depth in top-class stayers in New Zealand.
Here is a horse that has yet to start in an open company race, yet he has 55.5kg in a Wellington Cup.
It won't stop him.
Very noticeable was Green Supreme's seeming dislike of the right-handed way of going at Ellerslie. He is trained left-handed and should be much more comfortable going that way at Trentham.
Cassini is the horse that could fly under the radar. She put them away easily in the Manawatu and Wanganui cups, then failed completely to handle the wet track on City Of Auckland Cup day.
This will be a tough race. Cassini's trainer Mark Oulaghan gets his horse very fit and they are rarely found wanting in the final strides.
Richardson says he would not normally take three horses to a race like this without having raced for four weeks, but he says this time the extra week is working well for Green Supreme, Single Minded and Top Spot. "It was a hard slog at Ellerslie and Green Supreme definitely knew he'd been to the races."
Single Minded flew through his winning run, clearly getting some of his toughness from being bred from a Zabeel mare. "He's as tough as old boots and he's just thriving," said Richardson.
Top Spot came from last on the home turn to finish third behind Single Minded and Richardson believes the High Chaparral mare is underrated.
Crocodile Canyon was so decisive in running away from pretty ordinary opposition when winning last start he has to be given some consideration.
Allan Sharrock is walking a knife edge. The Taranaki trainer has tried to freshen Shez Sinsational from her brilliant 2000m Zabeel Classic victory to be sharp enough for tomorrow's 1600m of the Thorndon Mile.
The knife edge comes from the fact you still have to do enough to keep the horse fit.
"I have to say she's looking a bit porky, but then she's got a six-hour float trip to the races to tighten her a bit," said Sharrock.
"I tried to get fresh legs into her for the 1600m, but she might have done just a little too well."
For all that Shez Sinsational is a class act and Sharrock is more than happy with her 55.5kg.
November Rain's form on paper looks mixed, but she hasn't always had the best luck.
WELLINGTON CUP Green Supreme has burst on to the scene suddenly and is the $3 favourite.
It will be his first start in open company, but he looks better than most of the field.
Graham Richardson has three runners, Single Minded and Top Spot as well as the favourite.