Grunting at full volume, Maria Sharapova celebrated her return to the world number one ranking by outmuscling fellow Russian Vera Zvonareva to reach the Australian Open quarter-finals on Monday.
The top seed's 7-5, 6-4 win over the tournament 22nd seed means she will meet another Russian, 12th seed Anna Chakvetadze, in the quarters.
The 19-year-old pin-up moves up from second in the world rankings following Amelie Mauresmo and Svetlana Kuznetsova's elimination from the tournament and Justine Henin-Hardenne's absence.
Sharapova, who came within two points of being beaten in her heat-affected opening match, displayed lapses of concentration against Zvonerova and acknowledged she needed to improve against Chakvetadze.
"I thought I played a lot better today than I did in my previous rounds but I'll definitely have to step it up against her," Sharapova said.
"I don't know her game that well ... she's had some great results in the last couple of months and she's a big hitter and another young Russian that's coming up so I look forward to that."
Sharapova shrugged off her return to number one as "not that big of a deal".
"It's a good fact, but it's not something I go onto the court thinking about," she said.
"Probably at the end of the tournament, once you see it on paper again, it's pretty cool. It takes you back to the hard work and the results that you've had."
Sharapova and Zvonareva battled out a baseline slugfest from the first game and neither player was able to make a breakthrough as the 24th-ranked Russian matched her more famous compatriot's renowned tenacity chasing down returns.
Sharapova, a semi-finalist here in 2005 and 2006, knew she was in for a battle during a marathon ninth game that went to deuce seven times, with Zvonareva saving five break points to hold serve.
The leggy Russian said she appreciated a tough hit-out against Zvonareva ahead of the finals and felt she had raised her game a level.
"(Those were) probably some of the longest rallies I've had this week," she said. "Tougher situations point wise, holding your serve, again being breakpoints down."
Sharapova's relentless attack was finally rewarded with a break to go up 6-5, prompting an irate Zvonareva to hurl her racquet to into the court.
Sharapova served out the set while Zvonareva crumbled, admonishing herself between points and allowing her opponent to clinically take advantage of her mental disarray to take an early break in the second.
The reigning US Open champion raced to a 5-3 lead but also lost concentration, allowing Zvonareva a break to get to 5-4.
Sharapova then double faulted on one match point and blew another by mistakenly halting the rally to challenge the umpire's call before making it third time luck to wrap up the game.