Japan chop Chile in Kirin Cup
Okazaki smashed home Japan's opener after 20 minutes and added a second with a clinical finish four minutes later after latching on to Yuji Nakazawa's through ball.
Yuki Abe headed Japan's third seven minutes into the second half and Keisuke Honda completed the rout in injury time as Japan dominated the first of two warm-up matches before their final three World Cup qualifiers next month.
Japan play Belgium in Tokyo on Sunday in the final game of the three-team Kirin Cup before flying to Tashkent for the June 6 clash against Uzbekistan.
Victory over Uzbekistan would book Japan's spot in the 2010 World Cup finals in South Africa.
Chile are third in the South American World Cup qualifying standings below Brazil and above Argentina. They are away to leaders Paraguay in their next qualifier on June 6.