There are concerns over the welfare of BMW Hong Kong Derby favourite Waikuku after the rising star was found to be lame in his front left leg.

The John Size-trained gelding was examined, and treated, for sensitivity to the sole of his left front foot on Sunday, March 10, the Jockey Club announced in a release on Wednesday.

Size confirmed to stewards that Waikuku missed a day of work and has “restricted to slow work since the issue arouse”. The trainer said he intends to gallop the horse on Thursday morning.

Waikuku makes his mark, Callan Murray breaks through and Regan Bayliss knocked back

The issue means there is some doubt over the Irish import, who has been outstanding winning his past four starts, taking his place in the HK$18 million on Sunday.

Jockey Club chief vet Dr Peter Curl examined Waikuku on Wednesday and reported that he trotted sound with no additional findings of significance.

An update on Waikuku’s condition will be provided on Thursday.