The win was a relief for the German coach and the struggling defending champions as they have scored only one goal in the opening three games, which was the worst record for the capital club since the 1984-1985 season.
Mainz goalkeeper Robin Zentner had to be on guard to defuse Dani Olmo's effort in the 4th minute before Marcel Halstenberg headed just wide from a promising position four minutes later.
If Djokovic beats Schwartzman in the final, he will win a record 36th Masters title.
"I can see, Li Yingying has improved a lot, especially in blocks," Zhang added. Enditem
Brazil's Santos also moved within sight of a berth in the next round with a 2-1 win over 10-man Delfin in the Ecuadorian port city of Manta.
Former Barcelona midfielder Paulinho made it 2-0 for the defending champions in the 25th minute when another naturalized player Fei Nanduo, known as Fernandinho in Brazil, saw his shot parried by Henan goalkeeper Wu Yan, and the ball rebounded to the feet of Paulinho, who tapped it in.
In other action on Sunday, Jamie O'Neill took top spot in his group after two wins and one loss.
That has raised doubts over whether Zidane is going to face the same issues as last season, when his side at times struggled to score goals.
Ireland's Sam Bennett won the last stage after the eight-lap dash around the iconic Champs-Elysees to take the green sprinter's jersey.
Bologna went a player down in the dying minutes as Mitchell Dijks saw red after his second yellow card for getting a fistful of Alexis Saelemaekers' shirt. Enditem
Arrascaeta doubled the visitors lead by holding his ground while under pressure from Damian Diaz and then nonchalantly lofting a shot over Burrai that went in off the underside of the crossbar.