This tournament is clearly a different matter. Against Jankovic, whom she had beaten in their two most recent matches in 2007, Bartoli looked eager and determined. She took the ball on the rise, produced winners in bunches and feasted on Jankovic’s unimposing second serve.  “She doesn’t have a game that overwhelms you, so you get a chance to play,” Bartoli said. “I think I could have beaten a lot of women today.”  She will have a chance to beat Vera Zvonareva, the N0. 7 seed, in the quarterfinals after Zvonareva defeated Nadia Petrova, 7-5, 6-4.  The men’s draw has generated no major surprises here so far, with the top eight seeds advancing to the fourth round for the first time since 1970. Neither No. 1 Rafael Nadal nor No. 4 Andy Murray has dropped a set, with both winning their third-round matches on Saturday in impressive fashion.  Nadal, with his forehand setting the tone, overwhelmed the German veteran Tommy Haas, 6-4, 6-2, 6-2. Murray defeated Jurgen Melzer of Austria, 7-5, 6-0, 6-3.  On Sunday, No. 8 Juan Martín del Potro of Argentina became the first man into the quarterfinals by defeating another promising youngster, Marin Cilic of Croatia, in four sets.  But while the men have generally respected the form book, the women have been busy shaking the base of the tree, with Carla Suarez Navarro of Spain upsetting Venus Williams in the second round, Alisa Kleybanova of Russia upsetting Ana Ivanovic in the third round and now Bartoli hitting through the top-seeded Jankovic in the fourth.  Dinara Safina, the No. 3 seed, came as close as tennis allows to becoming the next victim, but she managed to escape in three sets against Alizé Cornet, a 19-year-old Frenchwoman.  After losing the opening set in a hurry, Cornet worked her way into the match, varying her spins and trajectories and giving Safina extra opportunities to lose her rhythm. Safina finished with 52 unforced errors to 32 winners and 8 double faults. But she has proven that she can stare down danger, saving match points in two different matches on her way to last year’s French Open final.  This time, she had to save two match points in the same match. Down by 2-5 in the final set, Safina won two games in a row. But Cornet then took a 40-15 lead on her serve. On her first match point, she nailed a forehand down the line that would have been a winner if it had not barely sailed wide.  She lost the next point with a backhand unforced error in the net. Safina was on her way and was the more aggressive, powerful presence down the stretch as she closed out a 6-2, 2-6, 7-5 victory.  “I hope next round will be more relaxing for me and my team watching me, because I think they have a heart attack watching me,” Safina said.  A semifinalist here last year, Jankovic now finds herself in danger of losing the No. 1 ranking, which would at least spare her further questions about how it feels to be atop the game without a Grand Slam singles title to her credit. Safina, Serena Williams and Elena Dementieva all have a chance to take over the top spot depending on their results here.  “I want to be the number one; I don’t want to be number two so I don’t have any pressure,” Jankovic said.  An illness kept Jankovic from playing in an exhibition in Hong Kong that she had planned to use as training for the Australian Open. This was her first tour event of the year.  “Today is not really a lack of playing,” Jankovic said. “My opponent was on fire today, hitting everything, going for her shots and most were going in."  It has not always been thus for Bartoli, who had never advanced past the second round in her seven previous appearances in Melbourne. Bartoli, 24, remains undersized for the modern game. She stands just a little over 5 feet 6 inches, but her two-handed ground strokes off both wings, inspired by the four-time Australian Open champion Monica Seles, allow her to create sharp angles and counterpunching power.  After losing weight and practicing exclusively with men during the off-season, Bartoli is moving better than she was at this same stage last year and was consistently able to extend rallies, even when Jankovic was dictating the flow of play. Bartoli also surprised Jankovic by varying the speed of her second serves, hitting some with the same pace as a typical first delivery.  “I was really determined this year to do everything I could to be ready,” Bartoli said.  She added: “I was just really determined to go back in the top 10, and I think I’m going in the right direction.”  A version of this article appears in print on , on Page SP9 of the New York edition with the headline: Bartoli Upsets Top-Seeded Jankovic, and It’s Not Much of a Fight. Order Reprints| Today's Paper|Subscribe
Jelena Jankovic was never able to change the flow of her fourth-round match with Marion Bartoli, which ended in a 6-1, 6-4 upset.