Defending champion Suzann Pettersen was ousted by England’s Jodi Ewart in the first round of the LPGA Match Play Championship on Thursday, while World No.1 Yani Tseng just scraped through.

Ewart, ranked 62nd, upset the third-ranked Norwegian three and one.

Fourth-ranked Ai Miyazato of Japan, another top seed in her quarter of the 64-woman field, also made a first-match exit, losing two up to Colombian Mariajo Uribe.

And Taiwan’s Tseng, who has already won three times this year, struggled to defeat South Korean Jeong Jang one up while World No.2 Na Yeon Choi of South Korea outlasted compatriot Grace Park two up.

Pettersen won the first two holes with a par followed by a birdie and even after Ewart answered with birdies with win the fourth and fifth holes, she birdied the sixth to reclaim a one-up lead.

But Ewart took command on the back nine, winning the 11th when Pettersen bogeyed the hole and taking the par three 12th and par four 13th with birdies.

Pettersen answered with a par to take the par four 14th but Ewart birdied the par three 16th and closed out the match with a birdie at the par four 17th.

Tseng won four of the first six holes, three of them with pars, to leap into the early lead over 64th-ranked Jang, but the last qualifier in the field began the back nine with a par and birdie to halve her deficit to two down.

Tseng won the par three 12th with a par, but Jang birdied the next three holes to square the match on the 16th tee. Tseng won the 16th with a par then matched Jang’s pars on the final two holes to secure the victory.

Uribe birdied the 14th, 15th and 16th holes to take a two up edge on Miyazato and won the par five 18th with a birdie to eliminate the Asian star.

Friday’s second round will see Tseng face 33rd-ranked American Katie Futcher, who ousted South Korean Chella Choi four and three, while Choi will next face World No.31 South Korean Jenny Shin, who downed compatriot Jimin Kang four and two.

Ewart will try to follow up on her upset of Pettersen by eliminating 30th-ranked Sophie Gustafson of Sweden, who beat England’s Karen Stupples four and three, while Uribe, ranked 61st, faces a second-round match with 36th-ranked Australian Katherine Hull, a three and two winner over South Korean Song-Hee Kim.

Also among those losing in the first round was Michelle Wie, who fell three and two to fellow American Mina Harigae.