Hong Kong racing royalty Romantic Warrior has come up just short in winning the world's most lucrative race, galloping to second in an epic finish against Japan's Forever Young in the US$20 million Saudi Cup in Riyadh.

Romantic Warrior – the highest-earning racehorse of all time – turned up at the Saudi capital for the race in the early hours of Sunday, Hong Kong time, hoping to add to the US$23 million already in the bank.

The seven-year-old horse led the pack until the final 50 metres of the race, when the Japanese dirt star rallied to surge ahead in a nail-biting finish.

This marked the first loss for Romantic Warrior since the Turnbull Stakes at Flemington in 2023.

Still, the Hong Kong-trained horse collected US$3.5 million for finishing second.

"He was gallant in defeat. We had a great pitch in behind and he got a little bit of kickback, so I thought I'll get him into clear air and he made ground just beautifully. He went through his paces really nicely all the way to the line and I can safely say I wasn't stopping. I did not alter my stride pace at all," said superstar jockey James McDonald.

"Of course, I'm gutted he got beaten ... but he went down on his sword that's for sure and made one hell of a race out of it."

Trainer Danny Shum, for his part, called the performance "a good run", noting Romantic Warrior was only beaten by a head.

"We all did our best. I hope to win every time, but racing is racing. As long as he tries his best and it's a really good race – I think most of the people enjoyed the race," said Shum.

The champion galloper is set to next tackle the 1,800-metre Group One Dubai Turf in April.