Radwanska had won the Auckland and Sydney titles prior to the season-opening Grand Slam and then romped into the quarters at Melbourne Park, building a 13-match winning streak.
She had also not dropped a set in 2013 until she lost 7-5 6-3 to Li in Tuesday's match and immediately replied that meant more work was on her schedule.
"I'm going to go now and practice, to the gym, running," she said when asked what she now planned to do after such a busy start to the season.
"No, I'm just kidding," she added laughing as she realised the punchline had been missed by the assembled journalists.
"No, please. No, of course I'm going to have a few days off definitely. I go home for a little bit. Then the next thing is Fed Cup, Doha, Dubai."
Radwanska, who lost to Serena Williams in the Wimbledon final last year, had beaten Li in the Sydney semi-finals prior to the Australian Open and had entered the match confident of advancing to her second Grand Slam semi-final.
The consistent Chinese, who won three of their four clashes in 2012, however, had stepped up her performance from Sydney, the 23-year-old Radwanska said.
"She was very solid from the beginning of the match," Radwanska said. "She was really playing good tennis.
"She's a very consistent player. She's always playing on the same level. It's not like up and down like the other girls. She's always playing solid tennis."
Neither player is known for having an overpowering serve, though Li's ability to capitalise on break points during the match proved the difference.
The 2011 French Open champion converted six of her seven break point opportunities, while Radwanska managed to convert four from 10.
Li also tightened up on her serve in the second set, with Radwanska having just three break point opportunities, two in the final game of the match, but Li reeled off four successive points, three from unforced errors, to clinch the victory.
"Some of the games she didn't let me do anything. Very deep balls all the time. Good serve.
"I had my chances. But when you're not really taking them, it's really turning around and it goes away.
"She was really playing good tennis today."