World number one Yani Tseng turned up the pressure on the leaders at the Sime Darby LPGA tournament in Malaysia on Friday, carding a four-under-par 67. The Taiwanese player\'s two-day total of six-under-par 136 puts her three strokes behind Stacy Lewis and Brittany Lang, who head the field. The $1.9 million tournament at the Kuala Lumpur Golf and Country Club includes nine of the world\'s top 10 golfers and Tseng, who has been in dominant form this year, has two more days to mount her attack. American Lewis joined compatriot Lang at the top of the leader board when she fired a six-under 65 in a round which contained eight birdies and one double bogey. Tseng, who got off to a slow start in round one on Thursday with a two-under-par 69, was cautious about expectations of a back-to-back tournament win after her South Korea victory last week. \"I try to focus on every shot, every tournament, every day, instead of thinking ahead,\" said Tseng, who has already won six tournaments this year, including two majors. \"Everybody tries to win every week so the most important thing you can do is do the best every day... and hopefully just play one shot at a time.\" Tseng had an inconsistent start in the morning, dropping shots on the fifth and ninth holes before picking up consecutive birdies on the sixth and seventh to finish on even par halfway through her round. She came alive on the back nine, playing solid golf and sinking four birdies on the 12th, 13th, 14th and 18th holes, the last putt, coming just before play was suspended due to bad weather. Tseng said she had time to plan her attack for Saturday. The tournament ends Sunday. \"Just like today, I’ll try to make birdies at every hole and if not, save par and then try to play smart. It\'s a tough golf course,\" she said. Play was suspended for more than three hours due to a thunderstorm but the delay did not spoil Lewis’ concentration as she birdied the 15th and 17th holes when play resumed to take a share of the lead. \"I struggled last week (in South Korea) and so it\'s nice to just get out there and shoot some good scores, and seeing putts going in is always a good thing,\" Lewis said. \"You\'ve got to make birdies I think. The golf course is a little easier this year so you have to make birdies and just keep it in the fairways.\" Following closely behind the leading duo is unheralded Dewi Claire Schreefel, the world number 204, from Holland, who is a stroke back. Also on eight-under is South Korea’s Choi Na-Yeon, ranked fourth.