* Serena puzzles with statements about match
* Meets young challenger to her mantle in quarters (Adds details, quotes)
By Greg Stutchbury
MELBOURNE, Jan 21 (Reuters) - Serena Williams was at her enigmatic best on Monday after she bludgeoned her way into the Australian Open quarter-finals with a 6-2 6-0 win over Maria Kirilenko.
The 31-year-old American wasted little effort in demolishing the 14th seed in 57 minutes to set up a showdown with young compatriot Sloane Stephens, yet as far as Williams was concerned she struggled against the Russian.
"I was surprised. I felt like Maria played really well," Williams told reporters. "I was just trying to play well, just to keep up."
Kirilenko tried to execute a high-risk game plan against Williams, but the third seed simply swatted her aside with contemptuous ease.
She served six aces to Kirilenko's one and her top speed for serve was 201kph. Kirilenko's was 170kph, three kph below Williams's average.
Williams's first serve completion was 87 percent and her second serve was just as potent with Kirilenko adding she thought she had made only one successful return.
Williams also gave up just three break-point opportunities, none of which the Russian converted. Williams converted five from seven. The American also hammered 22 winners and forced Kirilenko into 15 errors.
That dominance has continued a trend Williams began after twisting her ankle in her first-round clash against Romania's Edina Gallovits-Hall.
Last year at Melbourne Park, Williams entered the tournament with a badly injured ankle that she said contributed to her fourth round exit to Ekaterina Makarova.
This year, she is not taking any chances, blasting away at every opportunity. So far Williams has dropped just eight games and spent a total of four hours, 12 minutes on court although almost 10 of those were while getting treatment for her ankle injury against Gallovits-Hall.
Kirilenko simply shrugged her shoulders in her media conference after the match.
"I played like I want to play something unbelievable, every shot I want to do the good shot but sometimes you just have to play simple, maybe just through the middle," Kirilenko said.
"But when I played through the middle, then she started to make winners. Maybe I was trying too much.
"We didn't even have long points. It was really difficult to get the rhythm. It wasn't my day."
Williams will now meet the 19-year-old Stephens in the quarter-finals, a clash that could be seen as the handing over of the mantle of American women's tennis.
The pair met in Brisbane earlier this month and Williams said then she thought the right hander could be one of the best players in the world one day.
Williams, however, ruled out taking on any mentoring role for Stephens, or for that matter Madison Keys, and the teenager should be now be aware that there would be no sentimentality attached to the match.
"I would need a better definition of the word 'mentor'," Williams added. "I feel no responsibility. I doubt she has any expectations of me to be responsible for anything.
"I just feel like being the older one, probably maybe some of the younger players look up to me.
"(But) it's hard to be a real mentor when you're still in competition. I'm here to compete and do the best I can.
"I have a tough match, so we'll see." (Editing by John O'Brien and Alison Wildey)