Danny O'Brien will rely on stable newcomer Rios as his sole representative in Saturday's Listed Aurie's Star Handicap at Flemington after electing to save Vigor for the following week.Owned by Waikato Stud's Gary Chittick, Rios won six of his 20 starts in New Zealand before joining the O'Brien stable after his latest win in the Listed Anzac Hcp (1600m) at Awapuni on April 25."He's been with us for a few months and he's a nice horse, probably more of a miler but we obviously want to see him run a

Danny O'Brien will rely on stable newcomer Rios as his sole representative in Saturday's Listed Aurie's Star Handicap at Flemington after electing to save Vigor for the following week.

Owned by Waikato Stud's Gary Chittick, Rios won six of his 20 starts in New Zealand before joining the O'Brien stable after his latest win in the Listed Anzac Hcp (1600m) at Awapuni on April 25.

"He's been with us for a few months and he's a nice horse, probably more of a miler but we obviously want to see him run a forward race if he's going to get to a decent race," O'Brien said.

Steven King will take the ride on the Hussonet entire who is good fresh having won three times when first-up from five preparations.

Now a five-year-old, Rios won two of his three starts last preparation, winning over 1400m at Te Rapa when resuming on March 14.

Formerly prepared by Murray Baker, Rios had a three-race campaign in Sydney during the autumn of 2008 and was runner-up to Book Of Kells in the Group Two Tulloch Stakes (2000m) on a heavy track at Rosehill.

He was spelled after finishing eighth to his then stablemate Nom Du Jeu in the Group One AJC Australian Derby (2400m), also on a heavy track at Randwick.

As a spring three-year-old he landed a hat-trick of wins including the Group Two Breeders' Guineas (1500m) at Trentham where he defeated subsequent Toorak Handicap victor Alamosa by a nose.

Vigor, regarded by O'Brien as his best hope for the Caulfield and Melbourne Cups, will miss the Aurie's Star and resume at Caulfield on Saturday week.

"He's our best Cups horse," O'Brien said of Vigor who won five straight races, the last four of them at Flemington, over 1600m to 2520m from October to January.

2007 Cox Plate winner El Segundo heads the weights for the Aurie's Star with 63.5kg in what will be his fourth start in the Listed 1200m event after a soft 800m trial at Caulfield on Tuesday when trainer Colin Little said he was beaten "four or five lengths" with Luke Nolen aboard.

Now an eight-year-old, the Pins gelding ran last in 2005, second in 2006 and third in 2007 when the race was run at Moonee Valley.

Little said Sydney Cup winner Ista Kareem would miss the Aurie's Star.

The nine-year-old will resume in Saturday's Foletti & Keane Hcp (1410m) for which he is topweight with 61.5kg.