David Hayes is concerned a rain-affected Happy Valley track could thwart his speed machines Nervous Witness and Harmony N Blessed in Wednesday night’s Class Two Korea Racing Authority Trophy (1,000m).

The champion Australian trainer has a strong hand in the short-course sprint, but heavy rain and storms in Hong Kong have doused his confidence in his two charges.

Happy Valley was rated good to yielding on Tuesday and could be further downgraded with more heavy rain forecast on Wednesday.

Nervous Witness ran fifth on yielding-to-soft ground at Sha Tin in 2022 and a distant last on a wet all-weather surface at the same course last year.

Harmony N Blessed has had only one start on a good-to-yielding track, running third at Happy Valley last year.

“I prefer them both on top of the ground,” Hayes said. “Slow tracks slow them down a bit. I’d be more confident if it’s not raining.”

Hayes is hopeful his duo can still make an impact, with Nervous Witness recently breaking through for his first win in almost a year and Harmony N Blessed coming off a dazzling last-start win over 1,000m at Happy Valley.

A four-time winner in his first Hong Kong season before suffering from soundness problems, Nervous Witness returned to his best to lead all the way in the Class Two Rutland Handicap (1,000m) down the Sha Tin straight on March 3.

The Star Witness gelding has finished down the track in his two subsequent starts after being taken on for the lead on both occasions.

Hayes has opted to remove the hood from Nervous Witness in a bid to spark him back into top form on Wednesday night.

“If he gets left alone, he can dominate a race and look outstanding,” Hayes said. “The problem is, if he gets taken on he’s a bit of a one-trick pony – he over-races and doesn’t finish.

“He didn’t show his normal blistering speed from the gate last start so I just thought we’d tinker. He did win a lot of his earlier races without the hood, so hopefully that helps.

“He’s had soundness issues, but he’s very sound at the moment and he can easily run in this class.”

Harmony N Blessed also showcased his electrifying speed when leading all the way to beat Beauty Infinity by two and a quarter lengths in the Class Three Kowloon City Handicap (1,200m) at the city circuit last start.

However, Hayes believes the four-time 1,000m Happy Valley victor will sit off the lead on Wednesday night and still prove effective.

“Look, he doesn’t have to lead and I’d say coming back to 1,000m from 1,200m from [barrier three], I’d say he’ll follow the pace, where Nervous Witness is a one-dimensional speed horse,” Hayes said.

“I do think he’s probably over the years been better over 1,000m than 1,200m, so let’s hope he can get his highest-class win tomorrow.

“He’s been unsound as a young horse and he’s bled. He’s not bleeding at the moment and he’s very sound, so there’s no reason he can’t keep going at [a rating of] 84.”

Andrea Atzeni will ride Harmony N Blessed while Lyle Hewitson will pilot Nervous Witness, who jumps from the outside gate in a field of nine which also features Duke Wai, Whizz Kid, Seasons Wit, Majestic Knight, Carroll Street, Nordic Dragon and Humble Star.