Aus Open PIX: Nadal limps out, Edmund stuns Dimitrov, Wozniacki, Mertens make semis

Images from the quarter-final matches played at the Australian Open at Melbourne Park on Tuesday

Marin Cilic advanced to the semi-finals of the Australian Open on Tuesday after top seed Rafael Nadal retired hurt when trailing 3-6, 6-3, 6-7(5), 6-2, 2-0 in their match at Rod Laver Arena.

Nadal took a medical time-out late in the fourth set for treatment on an apparent hip injury and was clearly struggling as he battled on in the evening match.

After being broken to fall behind 2-0 in the fifth, Nadal called it quits, and shook hands ruefully with the chair umpire and Cilic.

Sixth seed Cilic will meet Briton Kyle Edmund for a place in the final.

Britain's Kyle Edmund bludgeoned his way past third seed Grigor Dimitrov 6-4, 3-6, 6-3, 6-4 on Rod Laver Arena to reach the Australian Open semi-finals.

The unseeded 23-year-old, playing in his first grand slam quarter-final, showed no nerves as he blazed away with his fearsome forehand to subdue a nervy Dimitrov.

The Bulgarian struggled to reproduce the form that saw him beat home favourite Nick Kyrgios in the previous round, with his serve especially vulnerable.

Edmund broke decisively at 4-4 in the opening set with a thunderbolt forehand off a weak second serve.

Dimitrov took the second set but never looked completely comfortable against the ultra aggressive Edmund and a double-fault at 3-4 in the third set proved costly.

The players swapped breaks in the fourth set but Edmund broke again for a 5-4 lead to serve for the match.

A tense final game saw Edmund double-fault but an ace brought up match point and then Dimitrov sliced a backhand long which was confirmed by Hawkeye.

Edmund is the only British man in the main draw after three-times grand slam champion Andy Murray withdrew to have surgery on his hip.

Elise Mertens produced another huge upset in a tournament littered with them when she thrashed fourth seed Elina Svitolina 6-4, 6-0 to reach the semi-finals of the Australian Open at the first attempt on Tuesday.

The aggressive Mertens smashed 16 winners to win the opening set and held her nerve to keep up the pressure on the world number four in a one-sided second stanza.

After barely putting a foot wrong in the contest, the 22-year-old fired down a 26th winner to seal a date with Caroline Wozniacki or Carla Suarez Navarro in her first Grand Slam semi-final.  

Former world number one Caroline Wozniacki marched into her second Australian Open semi-final by beating Spain's Carla Suarez Navarro 6-0, 6-7(3), 6-2 in the early hours of Wednesday morning.

After a one-sided start in a midnight match at Rod Laver Arena, Wozniacki met stiff resistance from the 39th-ranked Spaniard who dug deep to save a match point in the second set before outclassing the Dane in the tiebreak.

Second seed Wozniacki steadied herself, however, raising her game to bully Suarez Navarro from the baseline and grab another three match points on serve.

Wozniacki secured victory when Suarez Navarro hit long and she will meet Belgian Elise Mertens for a place in the final.

"I knew it wasn't going to be that easy ... In the second set I had the chance to close it out so I was disappointed I didn't do that," Wozniacki, who made the semi-finals in 2011, said on-court.

"I'm just proud that I managed to stay cool and finish it off in the third set," she added. "(Mertens) has had an amazing start to the year. It's going to be a tough one but I'm excited for it."