Wildcard Eugenie Bouchard showed she may have turned a corner as she attempts to resurrect her career with victory over eighth seed Caroline Garcia, while Alize Cornet beat world number 15 Petra Martic at the Auckland Classic on Wednesday.
Former world number one singles players Serena Williams and Caroline Wozniacki also breezed into the semi-finals of the doubles after they thumped top seeds Caroline Dolehide and Johanna Larsson 6-2, 6-1 in just 52 minutes.
Wozniacki and Williams, who are good friends off the court, have teamed up to play as a doubles pairing for the first time before the Dane retires after the Australian Open.
"Multiple times I was thinking 'wow'," Wozniacki said of the power strokes from Williams that blew the American/Swedish duo off court.
"I just wanted to win today. I'm happy for my second doubles victory in 10 years," the Dane added while laughing.
Both will play their second-round singles matches on Thursday.
Bouchard, a former top-five player who made the Wimbledon final and semi-finals at the Australian Open and Roland Garros in 2014, has slumped to 262 in the rankings and is attempting to resurrect her career.
The 25-year-old Canadian battled for every point in her 6-4, 6-4 second round victory against the Frenchwoman, who is mired in her own form slump having failed to advance past the second round of her previous 12 tournaments.
Bouchard will now face either promising American teenager Amanda Anisimova or Russia's Daria Kasatkina in the quarter-finals.
France's Cornet also provided something of an upset when she beat Croatian second seed Martic 3-6, 6-4, 6-4 in their second round clash and sealed the win with her only three aces of the match in the final game after she had gone 0-30 down.
"I lost the first set and it was not easy, but I came out of my comfort zone and I did a lot of stuff that I'm proud of," Cornet told reporters.
"I got through and that's the most important thing."
Muguruza powers her way into Shenzhen quarters, Wang advances
Garbine Muguruza won consecutive matches for the first time since last year's French Open when she beat American Shelby Rogers 6-1, 7-6(2) to advance to the quarter-finals of the Shenzhen Open on Wednesday.
The sixth seeded Spaniard, a two-times Grand Slam winner, fired 10 aces and won 80% of her first serve points to advance in an hour and 23 minutes.
"I think she started to play better and the match was more equal," Muguruza said.
"I was happy that at the end in the tiebreak, it was 50-50, and that I could win the match.
"Every match is very important and it's great to start the year here and get as many matches as possible. Every tournament is a challenge and I'm happy to keep playing."
Muguruza will face Kazakhstan's Zarina Diyas who beat Russia's Anna Blinkova 6-1, 6-7(9), 6-4 in a match that lasted two hours and 45 minutes.
Blinkova had upset top seed Belinda Bencic on Tuesday and despite breaking Diyas five times, she dropped serve nine times herself and made 11 double faults which proved decisive.
Fifth seed Ekaterina Alexandrova of Russia got the better of China's Peng Shuai, a former finalist, with a 7-6(7), 6-1 victory.
The home fans did have reason to cheer, however, when fourth seed Wang Qiang overcame Belarusian Aliaksandra Sasnovich, recording a 6-4, 0-6, 7-6(5) victory.
