Why does each SA20 captain name two team sheets before the toss?

Before the toss, each captain gives the Betway SA20 Match Referee two team sheets of 11 players: a batting-first version and a bowling-first version, plus the squad members available as substitute fielders and concussion replacements.

The toss takes place on the field between 30 and 15 minutes before the start. Once the winning captain chooses to bat or bowl (a choice that can't be changed), the matching team sheet for each side comes into effect. This lets both teams pick their XI to suit whether they end up batting or bowling first.

After nomination, a player in the XI can't be changed before play starts without the opposing captain's consent, apart from the concussion replacement rules. Only players nominated as substitutes may field as substitutes, unless the Match Referee allows additions in exceptional circumstances.