Caroline Wozniacki beat Carla Suarez Navarro to reach the Australian Open semi-finals and stay on course for a maiden grand slam title.

The sprightly world number two will face the unseeded Elise Mertens in the last four following a 6-0 6-7 (3-7) 6-2 victory on Rod Laver Arena.

It was 1.35 on Wednesday morning in Melbourne when the second seed sealed her place in the semi-finals of the first major of the year for the second time - seven years after first achieving that feat.

The 39-ranked Suarez Navarro raised her game to level the match after saving a match point in the second set, but was unable to reach a first grand slam semi-final.

Unseeded Spaniard Suarez Navarro looked like she did not know what had hit her as Wozniacki made a blistering start, dictating the play and defending resolutely to take charge.

Two missed backhands from the Canary Islands native gave Wozniacki the early break and a backhand winner put her 4-0 up in a flash.

The Dane demonstrated great speed and anticipation, wrapping up the opening set at a canter, but the diminutive underdog was much more assured in the second.

Suarez Navarro wound up her dangerous one-handed backhand with great effect, going a break up at 3-2 after Wozniacki made a couple of errors under pressure, but squandered that advantage by drilling a backhand wide to be pegged back at 4-4.

Wozniacki's frustration mounted as Suarez Navarro saved a match point and was rewarded for an aggressive approach in the tie-break, four mini-breaks bringing her level at one set apiece. 

It was Wozniacki who regained the initiative early in the decider, three unforced errors in the third game from Suarez Navarro giving the WTA Finals champion a break for a 2-1 lead. 

The 27-year-old remained on the front foot and a fierce volley gave her the chance to go a double-break up at 5-2 before serving out the match in the early hours.

STATISTICAL BREAKDOWN 
Wozniacki [2] bt Suarez Navarro 6-0 6-7 [3-7] 6-2

WINNERS/UNFORCED ERRORS 
Wozniacki – 34/21
Suarez Navarro – 31/39

ACES/DOUBLE FAULTS 
Wozniacki – 10/1
Suarez Navarro – 1/0

BREAK POINTS WON 
Wozniacki – 6/7
Suarez Navarro – 1/4

FIRST SERVE PERCENTAGE 
Wozniacki – 63
Suarez Navarro – 73

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE 
Wozniacki – 70/58
Suarez Navarro – 59/39

TOTAL POINTS 
Wozniacki – 98
Suarez Navarro – 76