The 36-year-old Spaniard has been sidelined with an abdominal strain and has played just one match since he was forced to throw in the towel in July's Wimbledon semi-final against Nick Kyrgios after suffering injuries.
Nadal looked rusty in the opener against grand slam debutant Hijikata, ranked 198 in the world, and dropped the first set.
After that, however, Nadal, who is chasing his 23rd grand slam title, picked up the pace and eventually won 4–6, 6–2, 6–3, 6–3.
- I am very happy to be back.
It's been a long time since I played here.
I thought I might never come back, says Nadal, who has not played in the tournament since 2019, when he became champion.
In the next match, Nadal will face Italy's Fabio Fognini.