Jockey Craig Williams says Black Caviar's first test over 1400 metres against last year's Caulfield Cup winner Southern Speed sets up one of the most exciting contests for the unbeaten champion.While stopping short of declaring an upset, Williams is genuinely excited about the prospect of a Black Caviar and Southern Speed showdown in Saturday's weight-for-age Group One CF Orr Stakes at Caulfield."It is great for racing," Williams said."Her (Black Caviar's) opposition has been becoming a bit mund

Jockey Craig Williams says Black Caviar's first test over 1400 metres against last year's Caulfield Cup winner Southern Speed sets up one of the most exciting contests for the unbeaten champion.

While stopping short of declaring an upset, Williams is genuinely excited about the prospect of a Black Caviar and Southern Speed showdown in Saturday's weight-for-age Group One CF Orr Stakes at Caulfield.

"It is great for racing," Williams said.

"Her (Black Caviar's) opposition has been becoming a bit mundane as the others try to avoid her but to run against a Caulfield Cup winner of the previous year who won so well first-up adds a little bit more to it this time."

Southern Speed is obviously a quality mare but Williams, who has been in career-best form, provides the X-factor.

He won the Caulfield Cup on the Leon Macdonald and Andrew Gluyas-trained mare as well as the Listed John Dillon Stakes (1400m) when she shouldered 60kg first-up at Caulfield on January 26.

Williams' other recent big successes have included the Cox Plate on Pinker Pinker, the Hong Kong Vase on Melbourne Cup winner Dunaden, last month's Karaka Million on Ockham's Razor in New Zealand as well as the Hai Stakes in Japan and the Meydan Masters International Jockey Challenge in Dubai.

He is hopeful that Southern Speed can provide Black Caviar with her most serious test so far, especially as she is untried over 1400 metres.

"I am hoping that over seven furlongs I won't need to have binoculars to see her backside," Williams said.

After Wednesday's barrier draw TAB Sportsbet opened Black Caviar, in barrier five, at $1.04 in the nine-horse field which is the biggest field the unbeaten champion of 17 races has contested since beating 10 rivals at her 12th race start in the TJ Smith Stakes (1200m) last April.

Barrier eight will suit Southern Speed who races off the pace and she is second favourite at $15.

Next in the market are Playing God ($41) in barrier seven and Black Caviar's stablemate Doubtful Jack ($51) in barrier one.

Another win on Saturday and Black Caviar equals the 18 wins a row posted by Ajax between 1937 and 1939.

Gloaming and Desert Gold share the Australian record of 19 wins in a row.