Jelena Jankovic has beaten Anna Karolina Schmiedlova in straight sets to reach the semi-finals of the Cincinnati Open.

The 2009 champion brought an end to what had been a fairytale week for the 20-year-old qualifier, who eliminated Agnieszka Radwanska earlier in the competition, as the Serbian won 6-4 6-2 in one hour and 50 minutes.

Jankovic broke her Slovakian counterpart in the fifth game to move 3-2 ahead, before Schmiedlova returned the favour to draw level at four games apiece in the opener.

However, the world number 25 hit straight back with another break of serve, and that gave her the impetus to clinch the opening set.

The pair broke one another's service in the first two games of the second set, before another break from Jankovic in the fifth saw her move 3-2 up as the underdog's resistance gradually waned.

Another break saw her fall 5-2 behind, and Jankovic held her nerve to win and book a last-four date with Simona Halep or Anastasia Pavlyuchenkova.