Seventh seed Anastasia Myskina edged past fellow Russian Elena Dementieva 6-3, 6-7, 6-4 to reach the semi-finals of the Zurich Open on Friday.
Myskina has known her fourth-seeded rival since childhood and their clashes are rarely memorable.
Friday's encounter proved to be no different, with both struggling to gain the upper hand in a match littered with errors.
After losing a 38-stroke exchange midway through the second set, Myskina responded by cracking her racket.
Dementieva, who won their last meeting in Moscow last week but had conceded their previous four matches, looked the better player tactically but failed to establish any consistency in the see-saw contest.
Myskina gained a 5-2 lead in the final set but within minutes she dropped her serve to love.
With Dementieva unable to capitalise on the break, Myskina held her nerve to clinch the match on her second attempt.
Serb teenager Ana Ivanovic took just 64 minutes to humble Slovenia's Katarina Srebotnik 6-3, 6-1.
Although she began by hitting a double-fault on the first point and dropping her opening service game, Ivanovic soon dominated with her serve and stronger baseline game.
She broke Srebotnik, who had upset second seed Amelie Mauresmo in the previous round, twice in the first set before sealing it with her seventh ace.
Trailing 3-0 in second set, Srebotnik was treated for a right abdominal strain and the delay momentarily disrupted Ivanovic's rhythm.
She fell behind 15-40 when play resumed, but two strong serves put her back to deuce and she went on to break to love in the final game to reach her first Tier One semi-final.
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