Jankovic through

Jelena Jankovic has progressed to the fourth round at the Australian Open after defeating Ai Sugiyama 6-4 6-4.

Jankovic, the 23-year-old world number one, took one hour 41 minutes to get past the Japanese number 26 seed to extend her run of wins against her to three following success in Doha and Indian Wells last year.

Sugiyama, playing in a record 59th consecutive grand slam main draw – and 60th in her career, went down a break early in the opening set and was always chasing from then on in.

Jankovic broke her opponent’s serve again in the seventh game when the Japanese world number 26 fired a cross court backhand wide but then failed to hold her own serve as Sugiyama clawed her way back to 5-4.

The 33-year-old Japanese player then appeared to get distracted in the next game when she disputed a late line call and subsequent challenge on Jankovic’s serve, believing the point should have been replayed rather than going to the Serb.

She was over-ruled by umpire Mariana Alves and from 30-0 up she lost the game and the set, although she did save the first set point against her.

The second set went with serve until Sugiyama was broken in the seventh game.

She then called for a medical time out where she had her calves iced and also complained of breathing difficulties.

However, she returned to see out the match, although she had further ice treatment to her calves.

The top seed will face Marion Bartoli in the fourth round after the French 16th seed defeated Lucie Safarova 3-6 6-2 6-1.