The World Test Championship final is the only occasion where a reserve day is added to Test match playing conditions, given the need for a result in the one-off, winner-takes-all clash.

Although the sun has been shining brightly all week at the Kia Oval, there is a slight possibility of rain or thunderstorms over the last two days of the competition. A significant amount of rain which interrupts play could result in the game spilling over into the reserve day in part.

In the last edition of the final, played at the Ageas Bowl in Southampton in 2021, the first and the fourth days of play were completely washed out, meaning New Zealand clinched victory at the end of the reserve day. In that scenario, given how much time had already been lost, it was clear that the entirety of the reserve day would be used to try and facilitate a result.

However, this time around, it is less clear when the reserve day, and how much of it, can be eaten into should a partial day’s play be lost to adverse weather or other delays.

The ICC regulations for the final define lost playing time as: “The minutes lost as a consequence of play being suspended for any reason other than normal intervals through the scheduled five days of the match, up to the start of the Scheduled Last Hour on the 5th day.”

There must be a minimum of 15 overs bowled in the final hour of play, which follows a minimum of 75 overs bowled on the final day of play.

If there is still lost playing time remaining to make up at the start of the last hour, the amount of time to make up will be converted into a minimum number of overs, one for every four minutes remaining to play. However many overs are calculated to remain will be played out before the start of the last hour. If the remaining lost playing time does not exceed one hour (converted to 15 overs), the playing times for the fifth day of the Test will be extended, and the reserve day will not be used. This is provided there are no further suspensions to play.

If the remaining lost playing time is more than 60 minutes, play can still be extended for up to an hour on the fifth day, to accommodate these overs. However, the last hour will not start.

The reserve day will then be used to play out the remainder of the lost time, in addition to the last hour of play. Thus, the reserve day shall only be used if the amount of lost time in the match exceeds one hour in total, before the start of the last hour on day five.

Despite a significant number of overs being lost throughout the ongoing final due to slow play, the reserve day cannot be used to make up those overs.