World number one Serena Williams opened her 2014 season with a hard-fought 6-4, 6-4 win over Germany's Andrea Petkovic in the second round of the Brisbane International on Tuesday.
Williams, who was given a bye in the first round, was pushed hard by the unseeded Petkovic in front of a packed crowd at Pat Rafter Arena.
The American mixed the good with the bad, making 36 unforced errors but hitting 35 winners in the 98-minute encounter.
The defending champion now goes on to face Dominika Cibulkova in the quarter-finals after the ninth seeded Slovakian beat 43-year-old Japanese Kimiko Date-Krumm 6-3, 1-6, 6-3.
Williams began well against Petkovic, breaking the German's second service game.
But any thoughts of an easy victory were quickly erased when Petkovic broke straight back.
In a close first set, both players had their chances until at 4-4 Williams seized on a loose service game to break Petkovic, then held her own serve to take the opener in 50 minutes.
The second set was as closely fought as the first, but with games at 2-2 Petkovic let a 40-0 lead slip to surrender the only break of the set.
She had a point to break back in the next game, but Williams held on and was never troubled on serve after that, claiming the second set and the match when a Petkovic forehand return hit the base of the net.
"It was an intense match, which was really good," Williams said.
"She's a good player. She's been in the top 10 before and she was on her way to being even better (before injury).
"It was a good match for me."
Williams said as soon as she saw the draw she knew it was going to be a tough match.
The two had only played once before, when Petkovic pushed Williams to three sets in Rome in 2010.
"I usually have a lot of nerves, but when I realised who I was playing I felt like, okay, she's going to be a really good match for me and a really good opportunity for me to have a tough match early on," Williams said.
"I think that kind of made me more calm than anything.
"My fitness is definitely where it should be," she added. "I felt great out there -- never actually felt winded."
Fourth seed Jelena Jankovic eased through to the quarter-finals almost unnoticed when she beat Elina Svitolina of the Ukraine 6-1, 6-3, the Serbian's second match on an outside court in succession.
Two seeds progressed in the men's draw.
Spaniard Feliciano Lopez (6) beat Mikhail Kukushkin of Kazakhstan 6-4, 6-4 and France's Jeremy Chardy (8) edged fellow countryman Adrian Mannarino 7-6 (7/4), 7-5.
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