Melbourne - Stan Wawrinka admitted on Saturday he was not impressed that long-time coach Magnus Norman decided to end their relationship as he battled back from knee surgery.

Norman called it quits on his four-year spell with the Swiss star in October after a partnership that saw spawned three Grand Slam titles.

He wanted to spend more time with his family, but it didn't go down well with Wawrinka who has not played competitively since Wimbledon in July and is gearing up for the Australian Open next week.

"No, for sure, it was already a tough, tough, tough moment for myself, to be out, to get surgery, to know that it will take at least six months to be back at a place where I can play tennis again," he said in Melbourne.

"It was tough to hear from him that he will stop at that moment.

"When you are in a tough place like that as an athlete, you want the people who know you the best to stay around you, to stick with you. You want your team, your family to be here.

"They will help you the most to get back where you want to be."

He said Norman was not only his coach, "but he was a friend, even closer than a friend" and he was "more sad than angry at him".

Wawrinka is still without a full-time coach, although he continues to work with Yannick Fattebert who plans to spend more time on the road with the 32-year-old.

Despite no longer being coached by Norman, Wawrinka said he would always be grateful for the time they spent together.

"That's what I want to keep from our relationship," said Wawrinka, who was the world number 17 and had never reached a Grand Slam semi-final before the pair hooked up.