Wales have been covering rugby balls in baby oil to prepare for humidity at the Rugby World Cup in Japan.

The technique is among a number tried as Wales build-up to their Pool D tournament opener against Georgia on Monday, 23 September in Tokyo City.

"We've been using wet balls and been using baby oil on them as well," said coach Warren Gatland.

"We've taped them up as well, and we've already been through that process in the [training] camps we had."

Gatland says preparations in Switzerland and Turkey were intended to help his players cope with the conditions in Japan.

"We have been to two camps where one was at altitude and it was very hot in Switzerland, and then it was the late 30s in Turkey," he said.

"We've done as much as we possibly can in terms of dealing with the heat.

"I think the humidity is going to be a factor. You can see how warm it is, but with the later kick-offs those temperatures are going to drop to about 20 degrees.

"It's going to be a lot cooler, but the challenge then is going to be the humidity and dealing with a slippery ball. It's how we cope with that.

"The players who have been to New Zealand will have experienced that. I come from Hamilton, it's incredibly humid there.

"We know what it's like and we have players who have experienced a lot of night rugby, so we feel we've prepared well. We are looking forward to it."

After facing Georgia, Wales play Australia, Fiji and Uruguay as they challenge for the quarter-finals in Gatland's final campaign in charge.

Watch Eddie Butler's Rugby World Cup preview, BBC One Wales, Monday, 16 September, 20:30 BST and later on demand.

Can't see this selector? Visit this page: Pick your Wales XV to play Georgia

All pictures via Huw Evans Images.