Second-seeded Karolina Pliskova hit 10 aces at Olympic Park Tennis Center to oust Russia's Maria Kirilenko, who needed a wild card to enter the tournament she won in 2008.
Maria Sharapova beat former doubles partner and childhood frined Maria Kirlenko 6-4, 6-0 in her opening game at the US Open.
Laura Robson stunned Russian 10th seed Maria Kirilenko with a straight sets win on Tuesday that ensured a female British presence in the second round at Wimbledon.
The defending champion Russian, seeded second this year, survived a nightmare start to hold on to her crown for at least another day with a 0-6, 6-4, 6-3 win over tough Jelena Jankovic in a compelling quarter-final tie.
Whether they are on friendly terms is another matter with the pair enduring an uneasy relationship since those childhood days, although both camps play down talk of a feud.
Kerber, ranked sixth in the world, broke Kudryavtseva 10 times, but dropped her own serve eight times to allow her Russian opponent to stay in the match.
Sharapova, seeking a first title since her 2012 French Open triumph gave her a career Grand Slam, will face former world number one Caroline Wozniacki of Denmark.
Kirilenko, who last year lost to Ana Ivanovic in the final, will take on Sorana Cirstea of Romania on Saturday.
Williams has lost only one match since her first-round exit at the French Open last year. Since then, she has won the Wimbledon, Olympic, U.S. Open, season-ending championship and Brisbane International titles.
There was no stopping the American, with Williams firing down her equal fastest serve of 207 kilometres per hour (128 mph) -- also clocked in round two against Garbine Muguruza -- on her way to taking the set in 31 minutes.
However Kirilenko, 25, said she had not yet set a wedding date with NHL player Ovechkin, who is also Russian.
Russian tennis player Maria Kirilenko has gotten engaged to compatriot ice hockey player Alex Ovechkin.
Lucie Safarova and Petra Kvitova breezed past their Serbian rivals to give holders Czech Republic a 2-0 lead in the Fed Cup final here on Saturday.
The Russian women's tennis pair of Maria Kirilenko and Nadia Petrova won the WTA Championships after beating Czech duo Andrea Hlavackova and Lucie Hradecka here in the final.
Russia's Maria Kirilenko weathered a tenacious performance from Yaroslava Shvedova of Kazakhstan to reach the quarter-finals of the Kremlin Cup tennis here Thursday.
A back injury forced former champion Maria Kirilenko of Russia to withdraw from a first-round match of the Korea Open on Wednesday.
World No.1 Victoria Azarenka beat Russia's Maria Kirilenko in straight sets to take the bronze for Belarus in the women's singles tennis at the London Games Saturday.
Maria Sharapova swept into her first Olympic final as the Russian world number three defeated compatriot Maria Kirilenko 6-2, 6-3 in the semi-finals on Friday.