Russia's Maria Sharapova battled back from a set down to beat Germany's Sabine Lisicki on Monday and reach the Australian Open quarter-finals, her best performance since lifting the title in 2008.
The fourth seed won 3-6, 6-2, 6-3 in 2hr 15 min to set up a last-eight clash with fellow Russian Ekaterina Makarova, who stunned Serena Williams earlier.
The 24-year-old Sharapova has now reached the quarter-finals or better in Melbourne five times, but this is the first time she has progressed so far since being crowned champion four years ago.
"I had lots of ups and downs today so I was fortunate to finish on a high note," she said.
"She was a good opponent and playing with confidence. I'm happy that although I didn't play my best tennis I hung in there."
Sharapova started with a blaze of attacking shots and broke Lisicki's first two service games with a series of punishing ground strokes.
But the gritty German refused to give in and slowly fought her way back into the match.
Using clever changes of pace and some deceptive serving, Lisicki didn't allow the much taller Sharapova to find any rhythm and the Russian's game began to fall apart.
Lisicki won the next six games to claim the first set in 36 minutes before Sharapova could stop the rot. The fourth seed then took control of the second set, breaking Lisicki twice to win the set and send the match into a decider.
The turning point came in the third game of the third set when Lisicki had five break points but couldn't convert any of them. Three games later Sharapova broke the German to gain a crucial 4-2 advantage.
Sharapova saved another break point to go to a 5-2 lead and brought up her first match point on Lisicki's serve.
The German held and forced Sharapova to serve for the match, but she kept her nerve and claimed victory on her second match point courtesy of a swinging serve to Lisicki's backhand.
The victory means Sharapova retains a chance of finishing the Australian Open as world number one, along with current incumbent Caroline Wozniacki, Petra Kvitova and Victoria Azarenka, all of whom are in the quarter-finals.