The tennis great wore a white sleeve on his right arm as he delivered the ceremonial pitch to Yankees catcher Austin Wells.
Tennis legend Andre Agassi said he can empathize with the controversial Nick Kyrgios and said he'd caution his critics "not to represent Kyrgios as if he should be loathed."
Defending champ Novak Djokovic suffered a major upset at the hands of unseeded Denis Istomin in a marathon 4-hour, 48-minute match at the Australian Open. Istomin is ranked 117th in the world.
Nick Kyrgios' effort in an Australian Open loss on Wednesday drew the ire of tennis legend John McEnroe.
Citing health setbacks as the main reason, former No. 1 player Ana Ivanovic, 29, announced her retirement from tennis on Wednesday.
Petra Kvitova suffered a "severe" left hand injury after being attacked by a knife-wielding burglar at her home in the eastern Czech Republic town of Prostejov.
