Tennis round-up: Impressive Wozniacki continues march in Auckland

Caroline Wozniacki continued to build on her WTA Finals victory late last year with another impressive performance on her way to a 6-2, 6-2 victory over Croatia's Petra Martic to reach the quarter-finals of the Auckland Classic on Wednesday.

The Danish World No 3 ended 2017 with the biggest title of her career in Singapore and returned a day after thrashing Madison Brengle in her season opener to hit 21 winners against eight unforced errors in the 53-minute win over Martic.

"I'm trying to stay aggressive," Wozniacki said in a court-side interview.

"I still made some unforced errors. It's taking a few matches to play like 100 percent but I still felt I played pretty well today."

Top seed Wozniacki started brightly with a break of serve to love on her way to an early 3-0 lead and added another break in the eighth game to wrap up the opening set in just 24 minutes on a glorious day in New Zealand's largest city.

Martic tried to mount a comeback early in the second when she broke for a 2-0 lead but Wozniacki won the final six games behind impressive serving numbers, including six aces, to book a last eight encounter with young American Sofia Kenin.

"I've worked on everything I need to work on in the off-season," Wozniacki added as she continues her preparations for the Australian Open starting in Melbourne on January 15.

"Now it's just a matter of working out how to incorporate that into your match or into a situation where you maybe get nervous."

Kenin, a 19-year-old wild card, knocked out compatriot Varvara Lepchenko 6-4 7-6(6) earlier in the day and there were also victories for Taiwan's Hsieh Su-wei and Barbora Strycova.

Hsieh eased to a 6-4, 6-3 victory over Belgian qualifier Ysaline Bonaventure to set up a quarter-final clash against Strycova after the third seeded Czech edged out Sweden's Johanna Larsson 6-1, 6-7(3), 6-2.

In the late matches, second seeded German Julia Goerges eased to a 6-4, 6-0 victory over Slovakia's Viktoria Kuzmova to book a last eight tie against Slovenia's Polona Hercog, who was almost as ruthless in a 6-4, 6-2 win over Kirsten Flipkens.

Former world number two Agnieszka Radwanska continued her strong start to the campaign with a 6-3, 7-5 win over American Taylor Townsend, the Pole holding her nerve in a tight second set that lasted more than an hour to advance.

Fourth seed Radwanska, who remains on a collision course for a semi-final against Wozniacki, next faces American qualifier Sachia Vickery, who defeated Paraguay's Veronica Cepede Royg 6-2, 6-4.

Halep rallies past Duan, ensures top billing for Australian Open

World number one Simona Halep assured herself of top billing for the Australian Open after powering past local hope Duan Yingying and into the quarter-finals of the Shenzhen Open in China.

Halep hit 21 winners and won five out of eight break points to prevail 3-6, 6-1, 6-2 and secure her number one ranking going into next week and top seeding for Melbourne ahead of Caroline Wozniacki and Garbine Muguruza.

However, the Romanian did not have it easy until her rival suffered a thigh problem late on in the match after blazing through the first set to take the lead.

Caught off guard by Duan's big hitting early on, Halep turned things around in the second set and broke the world number 91 twice for a 5-1 lead before levelling the contest.

Duan took a medical timeout and returned for the decider with heavy strapping on her left thigh.

Halep, who battled past Duan in their previous meeting in Eastbourne last year, took advantage as Duan struggled to find her rhythm and raced to a 5-0 lead. She then subdued a late fightback to seal the win in 97 minutes.

"I knew that she is playing really hard and hitting every ball. I knew I had to be strong on my legs," Halep said.

"After the first set I was thinking I have to find rhythm, to stay closer to the baseline and open the court better, which I did... It was a very tough match."

Halep's compatriot and fourth seed Irina-Camelia Begu overcame Russia's Ekaterina Alexandrova 4-6, 6-1, 6-2. She was joined in the quarter-finals by Czech Katerina Siniakova who beat China's Wang Yafan 7-5, 6-3.

Seeds Carreno Busta and Berdych suffer early exits at Doha

Second-seeded Spaniard Pablo Carreno Busta and third seed Tomas Berdych fell in the first round of the Qatar Open on Tuesday, losing in hard-fought matches to Borna Coric and Jan-Lennard Struff respectively.

Carreno Busta was expected to shine in his season-opening event after featuring in the 2017 ATP Finals but Coric came out on top in the two-hours-and-41-minutes encounter after launching an impressive comeback to win 5-7, 6-2, 7-6(8).

Coric held his nerve to beat the world number 10 and will face Georgia's Nikoloz Basilashvili in the second round.

"It was such a tough match," Coric said after the game.

"I think he was serving two times for the match and I was just thinking to myself (that) I was playing good for the whole match, and that was my main focus."

The CzechRepublic's Berdych slipped early in his match and lost the first set before recovering to win the second in dominant fashion. But German Struff dug deep to force a tie-break in the final set and went on to win 6-4, 1-6, 7-6 (4).

Struff, who is ranked 53rd in the world, will take on the winner of the match between Italian Paolo Lorenzi and France's Gael Monfils in the next stage.

Aljaz Bedene, now representing his home country of Slovenia again, set up a second-round encounter with top seed Dominic Thiem after beating Tunisian wildcard Malek Jaziri 7-5, 6-1.

Sixth seed Filip Krajinovic also lost to unseeded German Peter Gojowczyk, who will take on Italian Matteo Berrettini in the next round while eighth-seeded Spaniard Feliciano Lopez is set to face Bosnia's Mirza Basic.

Qatari Jabor Al-Mutawa was defeated by Italy's Stefano Travaglia, who fill face either fourth-seeded Albert Ramos-Vinolas or Argentine Guido Pella.

Mertens, Goffin find form as Belgium beat Australia in Hopman Cup

Elise Mertens fended off Daria Gavrilova while David Goffin blitzed his way past Thanasi Kokkinakis as Belgium secured a 3-0 victory over Australia in the Hopman Cup.

Mertens fought back from a set down to outlast Gavrilova 2-6, 6-4, 6-2 in a two-hour battle at the Perth Arena to help Belgium keep their hopes of reaching Saturday's final alive.

Gavrilova broke Mertens early in the match and clinched the opening set with ease. She continued to attack her rival in the second set but world number 36 Mertens saved a break point and changed her gameplan to counter the Australian.

"I started to be more aggressive, stepped up to the baseline and came to the net more," Mertens said. "I made her play more defensive, so I'm happy with my game in the end.

"I've worked a lot on my offence. Tennis at the top is so aggressive, so direct, that's the style I want to play."

Mertens reeled off three games in a row to level the contest at one set all and used the momentum to prevail in the decider.

Goffin, who beat world number four Alexander Zverev in his opening match, struck 27 winners in his 6-4, 6-2 victory over Kokkinakis to clinch the tie. Belgium then won the mixed doubles dead rubber.

"I'm feeling so well on the court since I arrived here in Australia," Goffin said. "I'm playing really well, I've won two good matches with a high level, so I'm very happy how I've started the year."

Belgium can reach the final if they beat Canada in their next match and Australia fail to better their result against Germany.

Earlier, Angelique Kerber beat Eugenie Bouchard 6-1 6-3 while Alexander Zverev defeated Vasek Pospisil 6-4, 6-2 as Germany sealed a comfortable 3-0 victory over Canada.