Right-handed pitcher Shota Onodera had a great outing for the defending champions, shutting down the Argentine bats for the sixth innings to claim the Group A win on Prime Ministers' Park Field

Japan stroke first in the third frame and added one more in the fifth to take a 2-0 lead.

They then scored three security runs in the bottom of the sixth, including a run batted in (RBI) triple by Natsuki Sato to the right field line and an RBI single by Kaito Miyamoto, and increased their advantage to 5-0.

In the top of the seventh, Argentina made it interesting with a two-RBI single by Gian Scialacomo that brought the tying run to the batter’s box.

But Onodera fanned Ignacio Sangoy to clinch the victory.

Today’s other matches in Group A saw Australia defeat India 4-1, and Mexico and South Africa overcome Denmark by scorelines of 12-1 and 3-2 respectively.

In Group B, hosts Canada beat the United States 10-3 after six innings.

The Canadians entered the bottom half of the sixth frame with a one-run lead, and then rallied to score six and end the game on the mercy rule.

Joining them in making a winning start were Czech Republic, who defeated Guatemala 7-0, and New Zealand, 10-0 victors at the expense of Hong Kong.

Preliminary-round action in Prince Albert is due to continue tomorrow.

In Group A, Mexico face India, Japan meet Denmark and Australia go up against Argentina.

Hong Kong do battle with Guatemala in Group B, while New Zealand and Canada play the US and Czech Republic respectively.

Six days of preliminary-round games will be followed by two days of play-offs and placement rounds before medal matches on July 15.