Jet lag is the first opponent as Norway prepare for World Cup opener in New Zealand

The Norwegian capital of Oslo is 10 hours behind Auckland, where Hege Riise's squad have been battling to recalibrate their body clocks after travelling halfway round the world.

"It's been both up and down but luckily it's beginning to sort itself out," defender Maren Mjelde told reporters. "I haven't experienced jet lag like it before, it makes you very tired."

Appearing at her fourth World Cup, she is no stranger to travel, and she and her team have been trying every trick in the book to get over the jet lag as quickly as possible.

"We've been clever and tried to do things all day - we have trained, we have been sociable and sat as long as possible at meals, all to try to get into normal routines," Mjelde said.

"Now I'm hearing more and more people say that they are getting into this time zone, so hopefully we're all there soon."

Norway will face Portugal in a friendly behind closed doors before kicking off their tournament against the hosts four days later, and that friendly will give them a good indication of whether they have managed to adjust to the time difference.

"We play Portugal on Sunday and, based on our training today, which was very positive... there was good energy today, so Sunday should go well," Mjelde said.

The team's support staff say it takes between five and seven days to adjust to the time difference, and Mjelde is aware that what works for one will not necessarily work for all.

"It's really very individual, how you tackle it. For my part, I've tried to stay awake as long as I can, especially the first few days. The closer you get to dinner time, around seven o'clock, you're pretty tired," Mjelde explained.

"It's about trying to hang on, find things to do, play games or read a book or solve a crossword or that kind of thing. I feel it's gone well, and I'm able to sleep longer into the mornings."

For Mjelde, there is one sure sign that her teammates are beginning to adapt.

"People are coming later and later to breakfast, so that's a positive thing," she said.