Both sides had chances to break the deadlock in the first half but missed them all.
Cirstea will face No. 20 seed Karolina Muchova of the Czech Republic in third round. Enditem
All of his youngsters have already left their marks and speak about their enormous ambitions.
The 23-year-old, who has previously been linked to interest from Spanish giants, Real Madrid and FC Barcelona, has agreed a contract until June 2025. He will travel to Manchester to join his new teammates after the Netherlands' UEFA Nations League game against Italy on September 7.
In the women's doubles, Xu Yifan from China and America's Nicole Melichar reached the second round after edging past their opponents in straight sets. Enditem
"Right now I'm really focused on the US Open, and nothing else I can think about right now," said Williams, who won six of her 23 Grand Slam singles titles at the US Open.
The first half saw tough play from both sides. Veteran Luiz Muriqui was subbed after just 23 minutes because of a thigh injury. Qingdao also made their first substitution a few minutes later.
Djokovic's exit means there will be a first-time Grand Slam champion in the men's draw.
In the other two clashes of the day, Hunan Hualai beat Zhejiang Energy to remain in third place, while Shenzhen Nankeda whitewashed Jiangsu in 5-0 to clinch their second win of the season. Enditem
After months of preparation, the ITTF announced the return of table tennis into the international arena and named it as RESTART.
Messi failed to appear for routine PCR tests on August 20 ahead of Barca's return to training, and did not attend any of the sessions under new coach Ronald Koeman.