Dubai - Former world number one Caroline Wozniacki withdrew from the Dubai Championships on Monday due to a viral illness before her first round match against Switzerland's Stefanie Voegele.
Wozniacki, who won the 2011 title in Dubai, also missed last week's Qatar Open because of the issue which she first felt around the Christmas period and the problem lingered with her through the Australian Open.
She failed to retain her Melbourne crown after losing to Maria Sharapova in the third round of this year's tournament and is yet to return to the court.
"It sucks. I've gotten ready to play these two weeks (Doha and Dubai) where I usually play well," the Dane said.
"If I can't even play at a reasonable level, there's no reason for me to go out there and just play one set - I want to go out there and I want to win," she added.
Wozniacki has been replaced by losing Slovenian qualifier Polona Hercog.
Doha champion Elise Mertens was eliminated after a three-hour struggle, losing to China's 107th-ranked Zhu Lin 5-7, 6-4, 7-5.
The Belgian received treatment at the two and a half hour mark for hip and leg problems as she felt the effects of last week's victory.
Lin, who's best Grand Slam performance came in losing at the third round of last year's US Open plays world number 23 Lesia Tsurenko next.
World number 56 in Tunisia's Ons Jabeur beat Croatian Donna Vekic 6-4, 7-6 (11/9) to claim a second round spot where she'll face the winner of the last two editions of the competition in Ukrainian Elina Svitolina.
With world number one and tournament top seed Naomi Osaka currently putting Asian women's tennis back on the map, Jabeur dreams of doing the same for her own continent.
"I'm now the Naomi Osaka of Africa," she joked. "It's inspiring to see how players can inspire a country or a continent.
"I'm trying to send a message that it's not impossible. You have to work hard. I want to see a lot of players from Tunisia to be here one day," he added.
Osaka was given a bye to the second round where she will face France's Kristina Mladenovic who won here first match of the season in the opening round.
Three US entrants secured their places in the round of 32 as Alison Riske upset 13th seed Julia Georges 6-4, 7-4. Sofia Kenin crushed Mihaela Buzarnescu 6-3, 6-0 and Jennifer Brady stunned former Roland Garros champion Jelena Ostapenko 6-4, 6-0.
"I was pleased with the way I was able to finish strong regardless of how I started the match," world number 117 Brady said.
Zhu Lin (CHN) bt Elise Mertens (BEL x16) 5-7, 6-4, 7-5
Carla Suarez Navarro (ESP) bt Barbora Strycova (CZE) 6-1, 6-3
Zhang Shuai (CHN) bt Anett Kontaveit (EST x15) 7-6 (7/3), 6-3
Ons Jabeur (TUN) bt Donna Vekic (CRO) 6-4, 7-6 (11/9)
Dalila Jakupovic (SLO) bt Zarina Diyas (KAZ) 1-6, 6-1, 6-2
Alison Riske (USA) bt Julia Goerges (GER x13) 6-4, 7-5
Sofia Kenin (USA) bt Mihaela Buzarnescu (ROU) 6-3, 6-0
Jennifer Brady (USA) bt Jelena Ostapenko (LAT) 6-4, 6-0
Katerina Siniakova (CZE) bt Petra Martic (CRO) 6-4, 6-3