Rusty Serena wins tough opener in Brisbane

World number one Serena Williams looked rusty in her first competitive match of the season ahead of the Australian Open but battled through to beat Andrea Petkovic 6-4 6-4 at the Brisbane International on Tuesday.

The number one seed won in 98 minutes to reach the quarter-finals but her 36 unforced errors and 55 percent serving accuracy showed how much Williams has to work on with the first grand slam of 2014 less than a fortnight away.

German Petkovic was exactly what the defending champion needed at this point in the season. Ranked 43rd in the world, but a top-10 player before injuries hampered her 2012 campaign, she ensured the five-times Australian Open winner had to fight for every point.

"It was an intense match, which was really good for me," Williams told reporters. "She's a good player. She's been in the top 10 before and she was on her way to being even better."

In their only previous match Petkovic took the American to three sets, on clay in Rome in 2010, and looked capable of doing so again after nullifying an early break and taking a 4-3 lead in the first set.

Williams held her serve to love and an easy missed volley into the net gifted the 17-times grand slam winner a break in the next, leading to Petkovic slamming her racket into thigh, floor and bag in turn.

In her first tournament match since the 2013 WTA Championships in October, Williams showed frustration throughout at the extent of her erratic play.

There were serves fired in at over 190 kilometers and 35 crunching winners, but even more mistakes.

After errant serves she would often practice her ball toss or technique, reinforcing the sessions spent with her father, Richard, in Florida during the off-season.

"I'm a renowned perfectionist - I think I wrote the book on being perfect," Williams said. "I think it definitely helps me in a way.

"Also, it definitely holds me back at some moments. It's just important for me to let the part that helps me kind of fill up and then the part that holds me back, just to let that go."