Australian rider Clayton Fredericks is looking forward to an advantage for early starters in the Olympic cross country event on the rain-soaked Beas River course in Hong Kong on Monday.

Riders and coaches got their first peek at the course, finding it mostly uphill and a stern early test with eight jumping efforts for the riders in the first minute.

Fredericks, whose British-born wife Lucinda is also on the eventing team, is expecting to be the first Australian rider to hit the course.

He believed riders would find it tough to complete the course in the allotted eight minutes.

"The course builder, you know, he has tried to ... sort out maybe the men from the boys early on," Fredericks told AAP as he walked the course.

Fredericks said the torrential rain of tropical cyclone Kammuri over the past few days had made the course "squidgy" in parts.

"I think it is really going to definitely be a bit of an advantage going early, possibly," he said.

"I am hoping it will be because it looks like I'm going first."

Fredericks said balance would be crucial as riders tackle the 29 jumps, which carry colourful titles including Five Coloured Lake, Tiger Hill Log, Phoenix's Lair and Big Leap to Success Water.

"It is very technical. There is plenty of places to have, you know, a silly run out," he said.

"If you are not 100 per cent on a good stride, you know, things could get a little difficult.

"It's a tough course. They're (the jumps) are well up in height - there is nothing easy about it."

At 4560 metres, the course is a little shorter than usual cross country tracks due to the humid conditions.

Coach Wayne Roycroft said it was an interesting course, which was very technical and had with a lot of angles.

The fences were large at the end of the course, he said.

"It is quite a tough test but a true test for the conditions," he told AAP.

"I think the course is very difficult to complete in time, and without any jumping penalties."

The eventing teams will take their horses through a trot up on Friday afternoon before the first test, the dressage, begins on Saturday at the Sha Tin Racecourse.

Weather conditions in Hong Kong eased. At 4pm (local time) typhoon Kammuri, which prompted a lock down in Hong Kong on Wednesday, was centred about 150 km south of Nanning.

It was forecast to move west at about 16 km/h towards the northern part of Vietnam.