Japan coach Eddie Jones has been hospitalised with signs of a minor stroke ahead of his squad's Test against New Zealand on November 2.
The 53-year-old Australian complained of a headache late on Tuesday when he returned to Tokyo from an inspection of the Brave Blossoms' training camp, a spokeswoman for the Japan Rugby Football Union said.
"He was with the team's staff at the time and they went together to a hospital in Tokyo by taxi," Mayuko Watanabe told AFP.
"The doctors said he was showing signs of a light cerebral infarction and he was hospitalised for examination."
Jones took over from All Black legend John Kirwan as Japan head coach in April 2012 and guided the Wallabies to the 2003 World Cup final, which they lost to England.
He has led the Blossoms to their fifth and sixth straight Asian Five Nations titles.
Jones has vowed to develop Japan into a top-10 rugby nation before the 2015 World Cup in England, as the Asian champions prepare to host the 2019 edition.
However, they finished fourth in the five-way Pacific Nations Cup last June.
The world champion All Blacks will play Japan in Tokyo, in their first Test on Japanese soil.