Belief key for Mertens after Aus Open exit

Elise Mertens won't be able to surprise opponents at grand slams any more after her stunning Australian Open run came to a halt at the semi-final stage.

The unseeded Belgian's tournament ended on Thursday when No.2 seed Caroline Wozniacki prevailed 6-3 7-6 (7-2) on Rod Laver Arena.

The loss ended a string of nine wins that saw the 22-year-old defend her Hobart International title.

In her first visit to Melbourne Park, Mertens upset seeded players Daria Gavrilova (23) and Elina Svitolina (4) during her unexpected charge to the last four.

Her world ranking shot from 37 before the Open to 20 and her semi-finalist's cheque for $880,00 AUD is more prize money than she's earned in her career.

Mertens is well and truly on the radar.

"I think that anything is possible," Mertens said.

"The belief in yourself.

"Also the second match, I was 5-0 down. I think mentally it's very important.

"Of course, the body has to work well too, but I think that anything is possible in tennis (after this)."

Wozniacki served for the match at 5-4 in the second and was 30-0 up before Mertens reeled off eight points to lead 6-5, before the set was decided in a tiebreaker.

But she committed a telling 35 unforced errors in the match to Wozniacki's 18.

"Caroline was really good ... she hit her serves and her groundstrokes were pretty aggressive," Mertens said.

"It's a mixed feeling ... I lost the match, but of course also I'm very happy that I'm in the semi-final, that I reach a semi-final for the first time.

"But I gave everything. I mean at 6-5, 6-all, you can see that the fighting spirit was there.

"But she was just slightly better than me today."