Japan emerged as one of the initial teams to profit from the fresh time-bound substitution guideline during Sunday's match, scoring as their rivals from Iceland operated with just 10 players on the field.

Several updated regulations from the International Football Association Board took effect ahead of the World Cup, requiring players to exit the pitch within 10 seconds at the closest boundary when being replaced.

Failure to comply means the incoming substitute must wait at least one minute for the next break in play, leaving the team temporarily short-handed.

In the friendly against Iceland, the visitors violated the protocol and winger Isak Thorvaldsson could not enter the action.

With Iceland reduced in numbers, Koki Ogawa headed home in the 87th minute to secure a 1-0 victory for Japan.

The decisive goal arrived one minute and 54 seconds after Thorvaldsson was blocked from joining the play.

After the contest, Japan coach Hajime Moriyasu cautioned his squad against repeating Iceland's error.

"I thought the players handled the new rule adjustments today with almost no issues," Moriyasu said.

"Under the new rules, players won't necessarily be able to get back on the pitch as quickly as before. That's something we need to be mindful of. Whether it's during substitutions or in other moments, we need to avoid creating openings that give the opponent a chance."

Moriyasu also highlighted the need for precise instructions during the new three-minute hydration breaks.

"In those three minutes, we have to organise the key points we need to get across and communicate them clearly to the players," the 57-year-old said.

"I felt that how well we use those three minutes could have a major impact on the outcome of matches, so we want to prepare thoroughly."

Japan open their World Cup campaign versus the Netherlands on Sunday, 14 June at 21:00 BST, followed by fixtures against Tunisia and Sweden.

This summer's World Cup features numerous regulation updates aimed at curbing time-wasting tactics and maintaining game tempo.

Fifa referees' chief Pierluigi Collina expects these measures to reduce lengthy stoppage times compared to the 2022 tournament, though three-minute hydration breaks are assured each half.

Throw-in countdown (five seconds): Deliberate delays result in the throw being awarded to the opposing side.

Goal-kick countdown (five seconds): Similar delays can lead to a corner instead.

Off-field treatment (one minute): Players receiving physio attention must remain off the pitch for 60 seconds, with exceptions for goalkeepers, serious injuries or opponent sanctions.

Players covering their mouths: Confrontational mouth-covering toward opponents may draw a red card.

Additional VAR adjustments include checks for corners and reviews of second yellow cards.

Corners can be checked: VAR may verify correct corner awards quickly before the restart, though wrongly given goal-kicks are excluded.

Second yellows can be reviewed: Players dismissed via two cautions may have the second booking examined, but potential second yellows receive no review.