Djokovic starts Australian Open defense

The top-ranked Djokovic faced only three break points, saving them all, and lifted his tempo when it counted most against Mathieu.

Djokovic's five-set win over Rafael Nadal in the 2012 final that lasted almost six hours is already part of Australian Open folklore. He tore off his shirt and flexed his muscles after the marathon win last year, and is hoping to add another chapter by becoming the first man to win three consecutive Australian titles in the Open era.

Nine others have won back-to-back titles: none have claimed three in a row since the Open era started in 1968.

"Any achievement, especially if it's part of history, would mean a lot to me," Djokovic said. "I love this sport. This sport is my life since I was 4 years old. I try to generate this great desire to play this sport from that love.

"I think it's too early, again, to speak eventually about the title because there are many contenders to win this title."

Djokovic, who lost to Australia's Bernard Tomic in the Hopman Cup this month, said his win over Mathieu, who reached a career-high No. 12 ranking in 2008, was a good stepping stone for his second-round match against American Ryan Harrison, a 2-6, 6-4, 7-5, 6-4 winner over Santiago Giraldo of Colombia.

Maria Sharapova and Venus Williams had nearly flawless opening matches in the women's draw earlier in the day.

Sharapova finished her first match of the year in 55 minutes, cruising to a 6-0, 6-0 win over Olga Puchkova on center court. She showed no signs of trouble with her sore right collarbone.

The No. 2-ranked Sharapova, who lost to Victoria Azarenka in last year's Melbourne final before going on to win the French Open, faced only two break points in her opener and she saved both of those in the first game.

Then she went on a 12-game roll that earned her a second "double bagel" inside of a year.

Sharapova withdrew from the Brisbane International this month with the collarbone injury, saying she wanted to concentrate on being fit for the first major of the season. She skipped the Brisbane tournament last year, and went on to reach the Australian Open final.

"After a couple of close games and a few break points, I certainly started to concentrate a bit better," she said. "I didn't want to concentrate on the fact I hadn't played a lot of matches. I just wanted to focus on what was ahead of me and really be aggressive.