Simona Halep is into the quarter-finals of the Australian Open after patiently dispatching Elise Mertens 6-4, 6-4 on Rod Laver Arena. Halep will face Estonian Anett Kontaveit as the 2018 finalist reaches the quarters in Melbourne for the fourth time in her career. Mertens blasted bags of winners but also made 38 unforced errors as Halep chased down every ball and kept making the Belgian put the ball back in play. The first set lasted 50 minutes and the Romanian had to grind it out, breaking Mertens twice – with the Belgian recovering one back in between – to eventually take it 6-4. Halep had to remain patient in the second as she broke in Mertens' opening two service games, only for Mertens to recover to make it 4-4. But Halep broke back in the following game with her fifth break point, before going on to record her second Grand Slam head-to-head win over the 16th seed. Halep said in her on-court interview: "It's a great performance by me to play again in the quarter-finals. I'm really happy to go through. "Last year I played Mertens in Doha and I was leading a set and 4-2 and I lost the match so I know that I have to stay focused until the end. "To be honest I got a bit nervous at 4-3, but I was strong enough to finish the match. " I had to calm down because when I get a bit nervous I get crazy on court so I had to stay cool, to get the energy from the box and go without thinking behind."