Diatchenko stunned top seed Dominika Cibulkova in the last round only to fall short in her quarter-final meeting with Russian compatriot Pavlyuchenkova at the WTA Premier event.
Pavlyuchenkova, ranked 30th in the world, prevailed 6-1 3-6 6-3 in Moscow to book a last-four showdown with Katerina Siniakova.
A dominant first-set showing from Pavlyuchenkova highlighted the 110-place gap between the pair in the rankings.
But Diatchenko has been in excellent form at the hard-court tournament and she fought back in the second with breaks in the first and ninth games.
However, Pavlyuchenkova needed just one break in the decider to wrap up the victory in a little over two hours.
Teenager Siniakova underlined her resolve with a three-set success over Italy's Camila Giorgi, the Czech winning 7-6 (7-3) 4-6 7-5.
Giorgi fluffed her lines when serving for the first set as the opener concluded with three consecutive breaks to take it to a tie-break.
It was there that Siniakova produced some of her best tennis, reeling off four consecutive points starting at 3-3 to seize the initiative.
There were 10 further breaks in a match littered with unforced errors, but it was the 18-year-old who came out on top.
Lucie Safarova emerged victorious from her clash against fellow top-five seed Svetlana Kuznetsova.
The 27-year-old recorded a 6-4 7-5 win and will meet Irina-Camelia Begu in the final four, with the Romanian having beaten Tsvetana Pironkova 1-6 6-3 6-2.