WARSAW, Poland -- Former Wimbledon finalist Agnieszka Radwanska says she is retiring from tennis after a 13-year career.

The 29-year-old Pole, who reached a career-high ranking of No. 2, says she is "no longer able to train and play the way I used to."

Radwanska won 20 WTA titles in her career. She reached the Wimbledon final in 2012, losing to Serena Williams in three sets. Radwanska also reached the semifinals at the All England Club in 2013 and '15, as well as reaching the French Open semifinals in 2014 and '16.

Radwanska says she's not leaving tennis completely, adding "it's time for new challenges, new ideas, equally as exciting as those on the tennis court, I hope."