PARIS (AFP) - Serena Williams swept into the Paris Open last eight with a comfortable 6-1, 6-2 win over Croatia's Karolina Sprem on Thursday, while second seed Jelena Jankovic battled to victory over China's Li Na. Home favourite Amelie Mauresmo overcame Romania's Monica Niculescu 6-1, 6-2 and third seed Elena Dementieva saw off Russian counterpart Anastasia Pavlyuchenkova. World number one Williams took just under an hour to dispatch Sprem and will meet French qualifier Emilie Loit on Friday for a place in the semi-finals. "I definitely think I was in control of the match today," Williams said. "(My return) could be better. It's better than it was, but I can work on it as well. "I feel better (than in the 6-1, 6-4 win over Iveta Benesova on Wednesday), not as rusty or as crazy, so hopefully tomorrow I can do what I did today and stay focused for the whole match." Jankovic prevailed 6-0, 3-6, 6-2 against Chinese number two Li, who had beaten the Serbian in their four previous hardcourt meetings. "There are certain players who always give you a hard time, no matter what their ranking is," said Jankovic, who now faces French teenager Alize Cornet. "Her game and her style of play don't really suit mine, she doesn't allow me to do what I want to do." Jankovic, who lost her world number one ranking after crashing out of last month's Australian Open in the fourth round, broke her opponent three times en route to taking the first set in under 20 minutes. Li has struggled with a persistent right knee injury since March last year but showed tremendous resolve in the second set, fighting back from 3-1 down to take the match into a decider. Her resistance finally ended when, having already been broken in the fourth game of the third set, a disputed line-call denied her a break of serve when Jankovic was serving at 4-2. The 18-year-old Cornet overcame an early setback to secure a 1-6, 6-4, 6-2 victory over Slovakia's Daniela Hantuchova, despite taking a heavy fall in the second set. Number eight seed Mauresmo produced a watchful performance against Niculescu, having destroyed Italy's Sara Errani 6-2, 6-0 in her first round match on Wednesday. "I was pleased with the match, even though it had a slightly different feel to the one yesterday," said Mauresmo, who will meet Polish fourth seed Agnieszka Radwanska for a place in the last four. "It was a longer match as well, despite the fact the scores were almost identical. The rallies were longer and the games were more competitive." Dementieva came from 4-2 down in the first set against the 17-year-old Pavlyuchenkova to win an attritional contest 6-4, 6-2. "I think she's very talented, but she needs a bit more experience, especially when playing against top 10 players," said Dementieva, the current world number four. "She was really close in that first set and we had a good fight. She was very aggressive on the court and she has a very solid game for such a young age."