A second Boston Celtics player is out after testing positive for COVID-19. The team announced Monday that forward Al Horford, 35, has tested positive for the coronavirus. He is in isolation was listed on the injury report for Wednesday's preseason game as out on health and safety protocols. Guard Jaylen Brown is also listed as out for Wednesday after the team announced that he tested positive for COVID-19 on Friday. For both players, the team said, "Further updates will be provided as appropriate."Boston Celtics head coach Ime Udoka also tested positive for COVID-19 last month and was forced to isolate. He is vaccinated and was asymptomatic, the team said.The Celtics begin the regular season on Wednesday, Oct. 20 in New York against the Knicks.