The Czech has now won eight consecutive games at the Caja Magica and will face wildcard Sorana Cirstea or Caroline Garcia in the last 16.
Rushmi Chakravarthy, Punam Reddy and Shruti Dhawan crashed out in the quarterfinals of the US $ 10,000 tournament
Serena Williams has defeated her compatriot in four straight matches since a defeat in the quarter-finals of the 2013 Australian Open.
Chin-Wei Chan of Chinese Taipei and Montinee Tangphong of Thailand will clash in the US $ 10,000 tournament final.
Petra Kvitova won her third title of the year as she fought back from a set down to beat Romanian Mihaela Buzarnescu 4-6, 6-2, 6-3 in the Prague Open final on Saturday.
Other nominees for the prize are Angelique Kerber (Germany), Petra Kvitova (Czech Republic and Caroline Wozniacki (Denmark).
Poland's red-hot world number one Iga Swiatek did not drop a game in her Saturday singles match against Romania's Andreea Prisacariu, sending Poland through to November's Billie Jean King Cup finals in decisive fashion.
Australian Nick Kyrgios was expelled from the tournament after going wild in the third set of his match against Casper Ruud.
A summary of Day Three's matches at the Wimbledon Championships.
Djokovic continues to lead ATP Rankings
Sixth seed Elise Mertens fell to Kaia Kanepi 0-6, 6-0, 7-5 and seventh seed Julia Goerges lost to American Taylor Townsend 6-4, 7-6(0).
World Number one Simona Halep and Japan's Naomi Osaka are among the players nominated for the Women's Tennis Association (WTA) Player of the Year award.
Images from Day 4 of the 2021 French Open in Paris on Wednesday.
Images from Day 6 of the French Open in Paris on Friday.
Earlier, Ukraine took a 2-0 lead over Japan as world number five Elina Svitolina took the first point of the Billie Jean King Cup era.
Djokovic is clubbed with Federer, Juan Martin Del Potro, David Goffin and Alexander Zverev.
Images from Day 1 at the Australian Open.
IMAGES from matches on Day 8 at the French Open
On a day when top seed Sloane Stephens survived a scare before beating Ajla Tomljanovic 4-6, 6-4, 6-4, Sakkari showcased supreme court coverage skills throughout her almost two-hour match against Bertens.
World number one Naomi Osaka was beaten in her opening match at the Dubai Duty Free Tennis Championships on Tuesday, losing to France's Kristina Mladenovic 6-3, 6-3 on her return to competitive action after winning last month's Australian Open.
IMAGES from Day 2 of the Wimbledon Championships from the All England Lawn Tennis and Croquet Club, London, on Tuesday.
Former US Open champion Del Potro fired down 11 aces and did not face a break point during the one hour, 33 minutes match.
Defending champion Donna Vekic, of Croatia, earned a hard-fought win over British wild card Gabriella Taylor 7-5, 5-7, 7-6(3).
Alexander Zverev got the better of older brother Mischa at the Citi Open in Washington on Thursday, winning their first meeting at an ATP Tour event 6-3, 7-5.
Novak Djokovic took a first unsteady step toward completing the calendar-year Grand Slam on Tuesday as the Serb laboured into the second round of the US Open with a 6-1, 6-7(5), 6-2, 6-1 win over dashing Danish teenager Holger Rune.
IMAGES from the matches played on Day 3 of the Wimbledon Lawn Tennis Championships at All England Lawn Tennis and Croquet Club on Wednesday
The 36-year-old Australian Open champion arrived in the Dutch port city at the weekend knowing a run to the semi-finals will move him ahead of Rafael Nadal in the ATP standings.
Zverev's serve played a big role in the victory, his third of the year, as the World No 3 won all but two of his first-serve points in the final, which lasted 74 minutes.
It was Kristyna's first win over a top-five ranked player and she will go on to play fellow Czech Barbora Strycova in the quarter-finals.
IMAGES from the Australian Open on Tuesday.
Images from Day 2 of the Wimbledon tennis championships in London, on Tuesday.
Images from Day 2 of the French Open matches played at Roland Garros on Monday
Rafael Nadal was made to wait before his second-round Rogers Cup match due to several rain delays but did his part to put the schedule back on track with a speedy 6-2 6-3 win over Frenchman Benoit Paire on Wednesday.
Wimbledon champion Garbine Muguruza notched up her first ever victory on Arthur Ashe Stadium with a 6-0, 6-3 win over American Varvara Lepchenko at the US Open on Monday.
Images from Day 2 of the 2020 US Open in New York
World number one Simona Halep swatted aside American Nicole Gibbs while Maria Sharapova was flawless in her straight sets victory over Romania's Mihaela Buzarnescu in the opening round of the Shenzhen Open on Monday.
Summary of sports events and persons who made news on Saturday
IMAGES from matches played on Day 4 of the French Open at Roland Garros on Wednesday
The returning Scot also announced his withdrawal from next week's Rogers Cup in Toronto.