Simona Halep admits she goes into the Australian Open under-prepared.

The world number one is on a five-match losing streak dating back to Cincinnati last August after struggling with a herniated disc in her back over the final months of the season.

She only started her competitive 2019 campaign this week, losing her opener to Ashleigh Barty in Sydney, and faces another tough first-round match in Melbourne against Kaia Kanepi.

It was the big-hitting Estonian who stunned Halep in the first round of the US Open last summer before going on to reach the last 16, where she took a set off Serena Williams.

Halep said: "I enjoyed the time at home a lot. Now I feel refreshed to start the year, but still I am a little bit back with everything, preparation and matches. But I don't complain. Everything was how I wanted. So now I have just to put my head down and to go and work.

"I feel good. I practised very well these days. I'm looking forward actually to start it."

The Romanian has bittersweet memories from 12 months ago at Melbourne Park having reached her third grand slam final only to suffer another narrow defeat, this time to Caroline Wozniacki.

Halep's efforts in the heat put her in hospital the following day but she finally got her slam happy ending at the French Open, defeating Sloane Stephens.

She said: "It's big difference I can say inside myself because I did what I wanted to do. I won a grand slam finally. Now I can say I'm a real number one. Before I said without a grand slam, you are not a real number one.

"I'm happy. I'm enjoying the time. Everything I've done last year made me be more relaxed. I try just to improve more in my game and see how good I can be in the future."

Among the more surprising coaching changes in the off-season was Halep's split from long-time mentor Darren Cahill, who wants to spend more time with his family.

Halep begins the season without a coach but acknowledges that situation cannot continue for too long.

She said: "For me it's a little bit tough to change the person I'm working with every day because I get attached to people, to my team. I cannot change fast. I didn't want to do that. I wanted to feel that I'm ready to take another challenge.

"Every time you commit to someone in your team, you have to give 100 per cent. So I was not ready in the off-season. Now I'm feeling that I'm getting better. At this level it is impossible without a coach. So maybe in the close future I will have someone."

While Halep looks to rediscover her winning touch, Naomi Osaka goes into a grand slam as a champion and favourite for the first time after her dramatic US Open victory.

Osaka was the eighth different winner of the women's title in the last eight slams but it would be a surprise if she did not achieve more success very soon.

The victory over Williams and everything that went with it swept the 20-year-old from Japan into a maelstrom but she has coped impressively and said: "I feel the same. I think it would be bad if I changed in three months.

"I feel like maybe more people want to take pictures. But for the most part I've just been doing the same things."

Osaka faces Pole Magda Linette in her first-round match on Tuesday.