Sempiternal's recent run of good form came out of the blue, but if anyone was wondering whether it would be short-lived and the four-year-old would sink back to obscurity, Happy Valley on Wednesday night provided the answer.

Sydney-based James McDonald may not have known a great deal about his opposition - part of the deal with jockey invitational races - or he probably would have elected not to engage with Supreme Flight over the extended mile.

Supreme Flight is probably at his best over 1,400m and Sempiternal, coming back from a 2,000m win, was going to outmuscle him however things played out, and McDonald would have been better placed to just let the other horse lead.

But the pair got tangled in a war for the lead in a sizzling 27 seconds around to the Football Club turn that probably ended McDonald's chance of halving the International Jockeys' Championship title, with the tempo putting the race on for a late-storming runner and Amazingly ran over the top of him.

Two facts emerged from the run - Sempiternal is versatile distance-wise and he is also well up to winning in Class Three even though his Class Four maiden had arrived at huge odds.