As the match moved deep into the fifth set, it became more about mental fortitude than technical skill. Zverev fought through nerves by moving forward and was rewarded by breaking Thiem at 4-3 with an aggressive forehand.
"A match like today, I just feel like Pironkova was serving well, she was hitting winners everywhere," Williams said. "Maybe I wasn't being aggressive enough. So I think it's more or less me adjusting my game in the second set and coming back and just trying to do better."
In a tight mixed doubles battle, Zheng Siwei/Huang Dongping rallied from one set down to overcome Feng Yanzhe/Huang Yaqiong 12-14, 15-14, 11-5, 11-8, helping Qingdao seal the victory.
PSG have confirmed seven COVID-19 cases recently, apart from the above four are Kylian Mbappe, Mauro Icardi and Marquinhos, who will still be unavailable for PSG's home game against Marseille on Sunday.
Elsewhere, Bayer Leverkusen cruised into the next round as Nadiem Amiri's brace rounded off the 7-0 goal fest against Eintracht Norderstedt.
Last season ended with failure to qualify for Europe and that saw the club begin a major clear out. Central defender Ezequiel Garay became a free agent, while Dani Parejo and Francis Coquelin were sold at a bargain price to nearby Villarreal and Spain internationals Ferran Torres and Rodrigo Moreno joined Manchester City and Leeds United, with Torres going for much less than most believe he is worth.
The third seeds were forced into a final-set tiebreak, where they saved a match point, before overcoming Muhammad and Townsend in a tremendous tussle 6-4, 3-6, 7-6 (9-7) and booked their ticket to the final.
Lucien Favre then brought on Marco Reus for his return after a long injury lay-off, and the German international paid back his trust seconds later, beating Weinkauf following a free-kick at the hour mark.
Trump, 31, opened his play in Milton Keynes, England with a 3-1 victory over Chinese teenager Fan Zhengyi before defeating David Lilley 3-0. He then settled for a 2-2 draw with Alan McManus in his last match and won the group without challenge.
"WTT Macao will be a table tennis show like no other before it. After months of waiting to see what this is all about, the time has come to raise the curtain for our first ever exhibition of World Table Tennis," Steve Dainton, WTT Director and ITTF CEO, declared.
The 28-year-old striker was one of seven players in the PSG squad who had tested positive recently. The other infected players include Kylian Mbappe, Mauro Icardi, Angel Di Maria, Leandro Paredes, Keylor Navas and Marquinhos.