She dropped the first set on a tie-break to Serbian Jankovic, a former world number one, but fought back to win 6-7 (10/8) 7-5 6-2.

Oudin has only played singles at two previous grand slam tournaments, losing in the first round at the 2008 US Open and at this year's Australian Open.

She had to win three matches just to secure a place in the first round at Wimbledon, and that run will have allowed her to become familiar with the grass courts.

For Jankovic, defeat means she failed to reach the fourth round of a slam for the first time since the 2006 French Open.

The 24-year-old looked to be struggling fitness-wise during the match and took a long medical time-out at the end of the first set, in which she saved four set points.

Both players had struggled to hold serve, with an early exchange of breaks followed by another which enabled Jankovic to move 5-3 in front.

However Oudin then reeled off the next three games, forced Jankovic to save set point on serve, and the pair eventually went to the tie-break.

Oudin’s big forehand was her obvious weapon and Jankovic was struggling to keep her on the backhand side, which by comparison was weak.

But a missed forehand allowed Jankovic to reach set point and she made no mistake.

Oudin broke at the start of the second set but Jankovic broke back swiftly, and the pattern was then repeated.

A second tie-break seemed likely but Oudin broke in the 11th game and then came back from 0-30 on serve to hold and level the match at one set each.

With Jankovic having seemed unhappy for much of the Court Three clash, it was hardly a surprise when Oudin broke at the start of the third set.

As Jankovic’s challenge crumbled, Oudin held her nerve to book a clash with either Agnieszka Radwanska or Na Li in the fourth round.