Winning streak ends: Agnieszka Radwanska surrenders to Li Na
Li became the first player to take a set off Radwanska this season when she edged a tight first set which saw seven breaks of serve, but she then lost the first two games of the second set to love.
China's Li Na stormed into the Australian Open semi-finals Tuesday with a 7-5, 6-3 win over Poland's Agnieszka Radwanska, who suffered her first defeat of the year.
Li became the first player to take a set off Radwanska this season when she edged a tight first set which saw seven breaks of serve, but she then lost the first two games of the second set to love.
However, Li then rattled off five straight games and saw off two break points when she served for the match at 5-3 to claim her sixth win in 10 meetings with Radwanska.
Radwanska had been on a run of 13 straight wins, including 26 sets unbeaten, after claiming tournament wins in Auckland and Sydney.
Li will face the winner of Tuesday's all-Russian quarter-final between world number two Maria Sharapova and Ekaterina Makarova in the last four.
Li, a 2011 Australian Open finalist, is now into her first Grand Slam semi-final since she won the French Open in 2011.