Former world number one Jelena Jankovic returned to somewhere nearer her best form on Thursday to upset Samantha Stosur and reach the semi-finals of the Dubai Open in her adopted home city. It is the eighth-seeded Serb\'s first semi-final of the year and also her best win for 12 months as she beat the fourth-seeded US Open champion from Australia 6-4, 6-2. Jankovic achieved it despite a slowly healing muscle tear in her left thigh which, she says, was originally \"five point five centimetres long.\" She mostly adopted a more assertive style than she once had, controlling more of the rallies, and reducing the amount of court she needed to cover. Stosur, by contrast, appeared subdued, looked travel-weary, and sounded as if she might be suffering from a cold. Having a base locally may have aided the livelier Jankovic significantly. \"I tried to make as many returns as possible, because her serve is one of the best, if not the best in the game, and it is not a typical serve,\" Jankovic said. \"I was trying to read it and lean to one side a little earlier. I think I did that pretty well and was in control much of the time. It\'s a long time since I have been in the final here, and that\'s what I\'m looking to try to do.\" It is seven years since she faced Lindsay Davenport in the final, and if she wins Friday\'s semi against Agnieszka Radwanska, the fifth seeded Pole, it will give Jankovic a chance of going one better than she did against the former Wimbledon and US Open champion in 2005. Jankovic survived a mini-crisis on her serve game in the seventh game when she came through three deuces, going on to make an important breakthrough for 5-3 in the next game. She broke much earlier in the second set, in the third game, but was unable to consolidate it. Three break of serves in a row followed before Jankovic held for 4-2 and then broke again with the help of a Stosur double fault. \"I felt flat, and maybe it is all catching up with me,\" said Stosur, referring to the travel from Australia to Switzerland for the Fed Cup and now here. \"But I can\'t make that an excuse.\" Stosur nevertheless felt that this week and last (in Doha), which brought five wins in the Middle East, is an improvement on her recent form which has yet to deliver another title since her great triumph in New York in September. Later a ruthless Radwanska came through to face Jankovic in little more than an hour. She allowed only three games to Sabine Lisicki, even though the Wimbledon semi-finalist from Germany is this week at a career-high world ranking of 13. \"I was playing much better than on other days,\" Radwanska said after her 6-2, 6-1 success. \"I was returning very well. She\'s a great server so I made sure I was prepared. \"I haven\'t played Jankovic for a few years, so it will be a challenge,\" she added, strangely overlooking the win she had over the Serb en route to winning the Pan-Pacific Open title in Tokyo five months ago. Their head-to-head record is 1-1.