Japanese horses have dominated the two main support races on the Dubai World Cup program at Meydan.

Dual Japan Cup champion Gentildonna was a narrow winner in the 2400m $US5 million ($A5.41 million) Group One Dubai Sheema Classic and Just A Way demolished the quality field at the $5 million Group One Dubai Duty Free (1800m).

For Just A Way, it was almost a repeat of his win in Tenno Sho in October last year, when he left a quality field, which included Gentildonna, in his wake with a powerful finish over the last 400m.

The race ran almost according to form, with South African Vercingetorix second and Britain's Dank third.

"We had two tactics. One was to get in good position from gate two or Plan B was to sit behind in midfield as we did in the Tenno Sho," trainer Naosuke Sugai said.

Yuichi Fukunaga kept Just A Way just behind Logotype, who did all the early running, and let him loose in the straight.

In the Sheema Classic, which traditionally gets one of the most competitive fields during the Dubai World Cup night, Gentildonna, ridden by jockey Ryan Moore, overcame a poor draw from post 12 to blitz past Cirrus Des Aigles and Ambivalent in the closing stages.