DHAKA: Serena Williams went out of the Australian Open as a back injury hindered the five-time champion against a rampant Ana Ivanovic.

The Serb came back from a set down to win 4-6 6-3 6-3 - her first ever victory over Williams in five attempts.

There had been reports before the match that Williams had a back problem, and so it proved, reports BBC.

"I almost pulled out. I`m such a competitor, I probably should have," said the world number one.

"I don`t want to blame anything. I feel like Ana deserves all the credit. I feel she played unbelievable today. I think she went for her shots."

Williams revealed that she did not know the exact nature of her injury but had been dealing with it for "a few days".

She added: "It`s not anything that`s life threatening or anything. I feel like it will get better. I just need a couple days off.

"Unfortunately I don`t have that in a Grand Slam."

The reigning French and US Open champion had been tipped by some to complete the Grand Slam of all four major titles in 2014.

"I have given up on that a long time ago," said the 32-year-old. "I feel like I don`t even think about winning four in a row.

"Maybe I can win four in a row, but it seems like in the one year it`s kind of difficult for me for whatever reason."

Ivanovic, 26, goes on to face Canada`s Eugenie Bouchard or Casey Dellacqua of Australia in the last eight.

"It`s amazing," said the 14th seed. "Honestly, I went on the court and I just wanted to play the best I could. I`m so thrilled."

BDST: 1054 HRS, JAN 19, 2014
RS