text: Martina Navratilova's brief stint as coach of 2012 Wimbledon runner-up Agnieszka Radwanska is finished. Navratilova, who won 18 Grand Slam singles titles as a player, and Poland's Radwanska, who is currently ranked No 9, issued statements on Friday to announce the parting. They announced in December that they would work together. Martina Navratilova watches Agnieszka Radwanska in action during this year's Australian Open . Radwanska has struggled this season and was knocked out in the first round in Stuttgart this week . Radwanska is only 13-11 this season, including a first-round loss on Wednesday in a clay-court tournament at Stuttgart, Germany. A statement posted to Radwanska's Twitter account thanks Navratilova 'for her time and efforts over these last few months' and calls it a 'great experience to work with one of the all time greats.' The post adds that the women 'agreed that as Martina could not commit 100 (percent) to the project then it was not going to work as a long term partnership.' The French Open starts on May 24. Radwanska plays a forehand during her defeat by Sara Errani at the Porsche Grand Prix on Wednesday .
target: Martina Navratilova could not commit '100 per cent to the project'
  The pair only started working together in December last year .
  Agnieszka Radwanska is struggling for consistency this season .
  The Pole slumped to an early defeat in Stuttgart this week .