London, 10 October 2011 | AAP

Samantha Stosur has qualified for this month’s lucrative WTA championships in Istanbul following Agnieszka Radwanska’s title win in Beijing.

Radwanska’s 7-5 0-6 6-4 win over German Andrea Petkovic ensured last month’s US Open winner made the cut for the $US4.9m end of season tournament in Turkey from October 25-30.

Stosur has won only one match in two tournaments since her triumph at Flushing Meadows, losing both times in three sets to Russian Maria Kirilenko.

Stosur has tournaments in Osaka and Moscow in the coming fortnight to find some winning form before playing in the tournament contested by the top eight players on tour.