[citation needed] In May 2008, Lertcheewakarn won her first pro title in singles at $25k Balikpapan, defeating the top seed Isha Lakhani of India, in straight sets.

In 2009, Lertcheewakarn received a main-draw wildcard into the Pattaya Open; she lost her first-round match against Shahar Pe'er, which lasted 52 minutes, 1–6, 0–6.

[citation needed] She received a wildcard to Pattaya Open, but lost in the first round to Chanelle Scheepers, in a two-hour-and-forty-minute three-set match in which Lertcheewakarn had a 4–1 lead in the second set.

She then received a wildcard to the Malaysian Open where she beat Ksenia Pervak in the first round in straight sets, making this her first WTA main-draw win ever.

In doubles, Lertcheewakarn reached a WTA tournament final, partnering Jessica Moore, they lost to Dinara Safina and Galina Voskoboeva in a close match.

[citation needed] At the US Open, Lertcheewakarn qualified for her second Grand Slam main draw, defeating Zuzana Kučová, Ashley Weinhold and Kristýna Plíšková in three tough matches.

Lertcheewakarn won the Al Habtoor Challenge, beat Bojana Jovanovski, Regina Kulikova, Simona Halep and Kristina Mladenovic en route.