Meanwhile, FIFA president Gianni Infantino restated FIFA's support for the football community during the crisis.
Last season's top scorer Pierre-Emerick Aubameyang completed the scoring ten minutes later, finishing off a fine team goal by curling home from Willian's assist.
Hoffenheim dominated possession and produced more promising chances but Horn was on guard to deny Kramaric and Pavel Kaderabek in the 18th minute.
"I have made the most difficult decision of my sports career. I will close this chapter in this wonderful football club where I have grown as a player for seven years... Triumphs, joys and also hard times but what I am most proud of is that I arrived in Munich as a young man full of dreams and now I will leave completely fulfilled with the club, a history and a culture," he commented. Enditem
Cao Yunding had a goal disallowed in the 19th minute after the Shenhua's scorer tripped Tong Lei inside the box.
The Seagulls kept pressing, however, and were back on level terms ten minutes into the second half when Leandro Trossard's effort squeezed past the unconvincing Kepa Arrizabalaga in the Chelsea goal.
Plans about the club's structure will be made in close contact with its 160,000 members who have to vote on any significant changes within the club.
Up to 20,000 fans will be allowed to enter the 79,000-capacity Maracana Stadium for Flamengo's home match against Athletico Paranaense in Brazil's Serie A on October 4.
In the women's tournament, Simona Halep advanced to the semifinals after Kazakhstan's Yulia Putintseva retired with the scores at 6-2, 2-0. She is to meet ninth-seeded Garbine Muguruza of Spain, who beat former number one Victoria Arazenka.
Earlier in the day, Zhaxi Yangben came first in the men's 50km race walk, with the winning mark of 3:52.19. Wang Rui finished second in 3:55.48, followed by Gong Fanglong in 3:59.01.
Li Ang netted a right-sided free-kick on 74 minutes to put the game beyond doubt, with a sweet finish for Suning.