Kim Clijsters, of course, was to win grand slams in a row, but it was not his best to grind the victory 7-6 6-3 Alize Cornet of France and a third-round match at the Australian Open on Saturday.
The third seed produced six double faults and a string of mistakes before getting a confrontation with Russian Ekaterina Makarova last 16, which disrupts the 13th-seeded compatriot Nadia Petrova.
"You never play a tournament playing your best tennis. And you too, you know, working for her. I think that's what I had to do today," said the Belgian Australian Open official site.
"Just little things that keep this pace or the pace to get where I want it to be."
Third-seeded Clijsters, became the first Grand Slam in 2011 as one of the favorites have retained their title at the U.S. Open last year, but after a good start in taking a lead of 3 to 1 in the first set, the errors start to creep in
Cornet Clijsters level Brokeback claim only his second break and pull back 5 to 4 September service.
But she was broken again after a mistake forehand volley left Cornet opportunity, she seized.
The first set tie-break, which was Clijsters 7-3, proved decisive Cornet also made unforced errors.
A break in the fourth game of the second was enough to seal the victory Cornet Clijsters, who has made a fine show of his 21 birthday.
Second seed Vera Zvonareva of Russia also has difficulties before claiming their place in the fourth round.
The world number two won 6-3 7-6 victory over Lucie Safarova of the Czech Republic, 31 seeds.
Zvonareva, chasing his first Grand Slam, took the first easily enough, but the second time, you do not need to win.
He finally won the tie-break, secured their passage with a balloon on the immaculate stranded Safarova.