MEMPHIS, TN, USA - Canada's Rebecca Marino is the only seeded player through to the quarterfinals of the $220,000 Cellular South Cup, after Melanie Oudin was dispatched on Wednesday. Third seed Oudin saved three match points when down 61 53 to Evgeniya Rodina, but that only delayed the outcome as the Russian advanced in straight sets, 61 75.

"I was definitely a little bit off today," said the 19-year-old Georgia native. "When I finally started playing better, it was too late. She was the better player today. She took control at the end and played a really good service game at 5-all."

Marino, seeded No.6, was also challenged but unlike her American counterpart found the answers - helped in no small way by 10 aces. The 20-year-old recovered from a break down in the decider to beat Romania's Sorana Cirstea, 62 46 63.

"I had to fight today and now I'm in my second quarterfinal," said Marino, who is through to her second WTA quarterfinal, having notched the first at Québec City last year. "I'm really happy. I hope I can keep it going."

Others winning through to the last eight on Wednesday included Lucie Hradecka, who beat fellow Czech Sandra Zahlavova, 64 63; and Coco Vandeweghe, who beat lucky loser Alexandra Stevenson, 62 62. Young Brit Heather Watson had a tougher time of it, riding a rollercoaster before overcoming Stéphanie Foretz Gacon, also a qualifier, 62 57 64.

"I started really well but she managed to raise her game and my game dropped," said Watson, who led 62 41 but soon found herself 4-1 down in the third. "It was a big fight in the end but I kept thinking, 'Stay calm, keep fighting and the opportunity will come.'

"I have played her three times and this was the first time I won. I actually played her last week and she won 8-6 in the third set tie-break. We have had some battles."

Eighteen-year-old Watson, who won the US Open junior title in 2009 and reached her first WTA quarterfinal at Auckland last month, faces Rodina in Thursday's quarters. Marino and Vandeweghe also face off, while Hradecka tackles Russian teenager Ksenia Pervak, who booked her berth on Tuesday. Magdalena Rybarikova and Alexa Glatch round out the match-ups.