Top seed Elise Mertens was knocked out as Daria Kasatkina won through to the Silicon Valley Classic final where she will meet Danielle Collins.

Fourth seed Kasatkina swept aside world number 17 Mertens in one hour and 21 minutes, winning 6-3 6-2 in San Jose.

The 24-year-old Russian progresses to her fourth final of the WTA season, claiming her third win from four meetings against the Belgian.

The win was former top 10 player Kasatkina's fourth triumph over a top 20 player this year.

Kasatkina broke Mertens three times throughout the match, never dropping her own serve, sending down 4-2 aces.

Mertens was not helped by seven double faults throughout the match, with Kasatkina saving the Belgian's only break point.

Kasatkina will face American seventh seed Danielle Collins who was too good for Ana Konjuh. Collins only needed 52 minutes to win 6-0 6-2 over the Croatian qualifier.

Konjuh struggled on serve throughout, with Collins breaking her six times, while she only won one from 17 points on her second serve.