She had to do it the hard way but 2008 champion Maria Sharapova has come from behind to beat Sabine Lisicki and reach the Australian Open quarter-finals, where she will meet fellow Russian Ekaterina Makarova following her stunning upset of five-time winner Serena Williams.
Things were much easier earlier in the day for Czech second seed Petra Kvitova, the reigning Wimbledon champion having no such problems in disposing of Ana Ivanovic 6-2 7-6 (7-2) and booking her place in the last eight where she will take on unseeded Italian Sara Errani.
It was far from vintage Sharapova as the No.4 seed had to overcome a huge momentum swing against her in the first set before she eventually wore down the German 14th seed, who will be ruing the one that got away following the 3-6 6-2 6-3 result.
A double break that gave Sharapova a 3-0 lead in the opening set was quickly forgotten as Lisicki reeled off six games on end to grab the first set and upped the ante further in the first game of the second set.
That game would go for nine minutes as Sharapova hit a forehand winner to stave off a break point, and her eventual hold of her serve proved pivotal as she broke in the fourth game to turn the match on its head and then did it again in the eighth game to force a deciding set.
And while the unforced errors continued to pile up for Sharapova, she simply would not be broken when it mattered including in the third game in which she needed 18 points to hold, and then again in the seventh game after she'd just broken Lisicki's serve.
Sharapova had a match point in the eighth game thanks to a Lisicki double-fault but yet another unforced error - she would finish with 47 to 29 - allowed her opponent to hang on, leaving the three-time major winner to serve her way to victory.
Earlier, world No.56 Makarova produced the match of her life to cause the biggest upset of the tournament so far in her 6-2 6-3 win over Williams.
Normally accustomed to blowing her opponents off the court, Williams met her match with an inspired Makarova more than matching it with the powerful American from the back of the court.
Makarova hit 16 winners compared to Williams' 24, but it was the unforced error count that really told the story with the 13-time Grand Slam champion committing 37 to Makarova's 17.
Williams' normally reliable serve also deserted her as she landed just 52 percent of first serves and won just 31 percent of points on her second serve. Her nine aces were also offset by seven double faults.
After games went with serve in the opening set, Makarova landed the crucial breakthrough in the fifth game before repeating the dose in seventh and then closing out a comfortable first set.
Williams grabbed the initiative in the second set with an early break, but Makarova hit straight back and then broke the 12th seed's serve again to edge closer to the finish line.
Serving to stay in the match, Williams saved three match points, but couldn't do it a fourth time as an errant backhand gave Makarova the biggest win of her career and her first quarter-final appearance at a Grand Slam.
Kvitova continued her march towards a second Grand