A baseball game between the Boston Red Sox and Toronto Blue Jays turned into one of the strangest sporting moments of the week after an unusual play appeared to produce a “fourth out.”

The bizarre incident happened during Tuesday's game in Toronto, forcing officials to stop the game and consult the rulebook before deciding what had actually happened.

How did the bizarre play happen?

The confusion began during the seventh inning when the Blue Jays appeared to score a run, but the Red Sox immediately challenged the play.

The situation became so complicated that umpires had to review the sequence and determine the order in which the outs and runners' actions occurred.

What made the incident particularly unusual was that the play appeared to involve an additional out after three outs had seemingly already been recorded.

Why was it called a “fourth out”?

In baseball, an inning normally ends after three outs.

However, the rules contain unusual situations in which an apparent fourth out can matter if a defensive player makes an additional out before the third out is officially completed and that out can eliminate a scoring run.

That obscure rule suddenly became extremely important during this game.

Officials in New York were contacted to review the complicated sequence, resulting in a delay while everyone tried to establish exactly what had happened.

Players were left wondering what was happening

The incident was so unusual that even people on the field were confused.

The game had to be paused while the umpires reviewed the situation and consulted the rules. The phrase “fourth out” quickly became the focus of discussion among fans and commentators.

Boston's interim manager Chad Tracy later described the play as extremely unusual, with the situation becoming one of the strangest moments of the game.

Why can baseball have such complicated rules?

Baseball has a number of unusual rules concerning force plays, runners, tagging and the timing of outs.

Normally, once the third out is recorded, the inning is over. But the rules allow certain defensive actions involving a potential fourth out to determine which runner is legally out and whether a run should count.

These situations are extremely rare, which is why even experienced players and spectators can find them difficult to understand when they happen in real time.

The game had to be stopped to solve the mystery

Rather than immediately making a final decision, officials reviewed the sequence carefully.

The unusual situation required consultation with MLB's replay officials, demonstrating how modern baseball combines on-field umpiring with video review when a complicated rule situation arises.

One play turned into a rulebook lesson

What began as an ordinary baseball inning suddenly became a lesson in one of the sport's most obscure rules.

The incident also shows why baseball can be so unpredictable. A play that looks straightforward to spectators can sometimes involve several technical rules governing exactly when a runner is out and whether a run counts.