Nadal had said that he did not know if he would be fit to play against Australian Kyrgios, after appearing close to retiring mid-match against Fritz on Centre Court.
Thiem, who also played in the charity event but did not contract the virus, told Austrian media that Kyrgios had "made a lot of mistakes" and should not criticise others.
Kyrgios, 25, recalled a time in Shanghai when he "didn't want to see the light of day".
The Australian's determination to once again display his talent on the Wimbledon lawns is an illustration of the huge importance the grasscourt Grand Slam has played in his career.
Almost 12,000 people have signed an online petition calling for the USTA to work with the country's government to allow Novak Djokovic to compete in the US Open despite his refusal to take the COVID-19 vaccine.
Kyrgios added that he had been in communication with Tennis Australia chief executive Craig Tiley and United Cup tournament director Stephen Farrow about his injury.
IMAGES from Day 10 of the Wimbledon 2022 Championships at the All England Lawn Tennis and Croquet Club in London, on Wednesday.
Two days after being named in Australia's Olympic tennis team, Nick Kyrgios said he is "tossing up options" and may opt out of the Tokyo Games due to COVID-19 restrictions.
Kyrgios was due to play Spain's Roberto Bautista Agut in the first round in Rome, but was replaced by lucky loser Alexandr Dolgopolov in the men's draw.
The young royal was urged to not drop the prized Wimbledon trophy by his father after being handed the trophy by Djokovic.
Australia's Nick Kyrgios pulled out of the French Open after failing to shake off a persistent elbow injury that has troubled him in the past few weeks, the 23-year-old announced on Sunday.
The frustrated 24-year-old shook hands with his opponent and the umpire before he strode off the court, effectively defaulting himself from the contest.
Nadal always looked like the most likely winner once he got his nose back in front.
A 55-shot, marathon rally brought fans to their feet in Flushing Meadows on Friday but nearly leveled the two men who lived through it, Norwegian Casper Ruud and Russian Karen Khachanov, competing in their US Open semi-final.
Nadal appeared close to retiring mid-match but found the will to beat Fritz
A summary of Sunday's action at the US Open.
Novak Djokovic has only faced Nick Kyrgios twice in his career, losing twice to him in 2017, so while he will be favourite to claim a seventh Wimbledon crown, he knows exactly how dangerous the unpredictable world number 40 Kyrgios can be.
Greek fourth seed Stefanos Tsitsipas labelled Nick Kyrgios a "bully" with "an evil side" to his character after losing a bad-tempered Wimbledon third-round clash on Saturday.
Rafael Nadal dug deep to beat mercurial wildcard Nick Kyrgios 7-6(0), 5-7, 6-4 in a blockbuster quarter-final match that lived up to the hype at Indian Wells on Thursday.
Simona Halep ended Beatriz Haddad Maia's dream run in Toronto
Australian controversial tennis star Nick Kyrgios has been slapped with the largest fine at the French Open for uttering an audible obscenity during his third round loss to Richard Gasquet.
Fourth-ranked Carlos Alcaraz and Norway's world number seven Casper Ruud also have a shot at top spot.
Australian Nick Kyrgios produced another extraordinary performance to demolish compatriot Alex de Minaur 6-2, 6-3 at the Canadian Masters on Thursday, a day after stunning world number one Daniil Medvedev.
The pair faced each other 40 times over the last two decades in one of the sport's most enduring rivalries, with the Spaniard leading the head-to-head 24-16.
Top seed Novak Djokovic set up a blockbuster Wimbledon final against Nick Kyrgios after recovering from a torrid start to overwhelm Britain's Cameron Norrie 2-6, 6-3, 6-2, 6-4 on Friday.
Andy Murray has defended using an underarm serve in his Wimbledon opener on Monday, saying it was a legitimate way to make opponents think twice
Nick Kyrgios cranked down 42 aces as he opened his Wimbledon campaign with 7-6(3), 7-6(4), 6-7(5), 6-3 win over Uzbekistan's Denis Istomin on Tuesday.
Stefanos Tsitsipas said that his victory in the final of the Mallorca Championships on Saturday was a major milestone in his career as the Greek claimed his maiden grasscourt title leading up to Wimbledon next week.
Evans, who recovered from illness to be part of the $15 million prize money event, showed his battling qualities to overcome Ramos-Vinolas
Australia's Nick Kyrgios said on Thursday he is unlikely to play at the French Open due to concerns about COVID-19. Kyrgios, who on Sunday announced his withdrawal from the US Open, told Australian television he plans to wait until it is safer to return to the tour.
'But I'm sitting out for the people, for my Aussies, for the hundreds and thousands of Americans that have lost their lives, for all of you. It's my decision.'
Australian Nick Kyrgios served like a demon to bounce Serbia's world number two Novak Djokovic out of the quarter-finals of the Acapulco International with a 7-6(9), 7-5 victory on Friday.
Amid the mental fight was Nick Kyrgios's usual array of the stupendous and stupid - under-arm serves, a record-breaking 145mph second serve, deft slices and, in the final tiebreak, shocking errors.
Tennis strategy analyst O'Shannessy, who was a part of Djokovic's team for both times the two players met, reveals...
After Nick Kyrgios, another Aussie involved in verbal volley as tempers flare in Ohio.
Australian Nick Kyrgios has hit out at Alexander Zverev after a video appeared to show the German dancing at a crowded club on Sunday despite the world No. 7 pledging last week he would be self-isolating. The video was posted on Instagram by German designer Philipp Plein and later deleted. There was no indication when the video was taken.
Kyrgios said he would consider resting until the Davis Cup finals in Madrid in November.
There was a back and forth until the Aussie forced the German great into submission.
Alex De Minaur and Nick Kyrgios fell to the ground in relief and celebration after winning the half hour-long extended tiebreak
The explosive and temperamental 24-year-old Kyrgios has a history of notorious outbursts and is being investigated for potential rule violations after calling the ATP Tour "corrupt" during the US Open last week.