World number one Maria Sharapova retired in the second set of her Pan Pacific Open semi-final against Serbia’s Ana Ivanovic due to a hamstring injury.

Ivanovic will play second seed Martina Hingis in the final of the 1.3 million dollar tournament after the Swiss beat Russian Elena Dementieva 6-4 6-3.Sharapova, trailing 1-6 1-0, said she felt a sharp pain after serving in the second game of the first set, adding that she had been carrying a hamstring strain since the Australian Open.‘’It’s always difficult to end the tournament this way,’’ the 19-year-old Russian told reporters.‘’My left hamstring has been having tightness since the Australian Open but after a Grand Slam you are tight all over,’’ said Sharapova, who lost to Serena Williams in the Melbourne Park final last weekend.Hingis avenged her defeat by Dementieva in last year’s final to stay on course for a record fifth Tokyo title.‘’I had a bad experience against her in last year’s final and I was happy to get more than two games,’’ said Hingis, who lost 6-2 6-0 to Dementieva in 2006.