Watch match highlights between defending champion Melanie Oudin against qualifier Ajla Tomljanovic.

Defending champion Melanie Oudin lost in straight sets 6-3, 6-1 in the first round of the Aegon Classic to world No.155 Ajla Tomljanovic.

At the scene of her only previous WTA tour triumph, Oudin struggled in cold and windy conditions against the Croatian qualifier, and after a close first set lost comfortably in the second.

Tomljanovic’s victory was based on a strong service, with a 70% first serve percentage.

Speaking after her match Tomljanovic said: “My serve was a big factor. I felt really comfortable returning and that meant I could go for more on my serve.”

Tonljanovic will play No.1 seed Kirsten Flipkens in the next round.

Keothavong vs. Riske

Anne Keothavong became the first British player to exit the 2013 Aegon Classic as she lost 7-5, 6-2 to American qualifier Alison Riske.

Talking post-match Alison Riske said: "It felt so awesome to be able to play on such a beautiful new court today. I felt honoured for sure. I felt right at home and the court looked great." 

Competing on the Ann Jones centre court Keothavong, apart from a break early in the first set, could not get make an impact on Riske’s serve.

After the close opener, Keothavong could not find consistency on her serve, eventually going down 6-2 in the second set after 1 hour and 32 minutes of play. 

Keothovong spoke after the match: "In the first set I played some good tennis but had poor errors at unfortunate times in the match. She served really well and hardly missed a first serve in the second set."

Elsewhere American Jamie Hampton defeated 10th seed Su-Wei Hsieh 6-2, 6-3.