$ 0 0 Chinese fourth seed Li Na was forced to dig deep against teenager Belinda Bencic at the AustralianOpen on Wednesday before blasting past the promising Swiss qualifier in straight sets. With the temperature hitting 38 Celsius (100.4 Fahrenheit) before the pair even stepped on court at 11:00 am, Li booked a third round berth with a 6-0, 7-6 (7/5) victory in 80 minutes. While the first set was a breeze, the second was a serious workout for the Chinese star who has made the final at Melbourne Park twice before, including last year when she lost to Victoria Azarenka."It was a little bit warm out there," said Li. "I am pretty happy. At least I won the match and am still in the tournament." Li, 31, is one of the oldest women in the draw and she had already handed out a lesson to the youngest player during the first round when she beat Ana Konjuh, 16.