(Reuters) - Red card replacements are among three innovative laws set to be trialled in this year's Rainbow Cup after being approved by World Rugby, organisers Pro14 said on Thursday.
Players who receive a red card can be replaced 20 minutes after they are sent off by one of the team's nominated replacements.
Captains will be allowed one challenge per match to review try-scoring and foul play, or to challenge any decision in the last five minutes.
The defending team will also be allowed to drop out from their goal-line when the attacking side are held up over the line.
Variations of the laws are already in use in New Zealand's Super Rugby Aotearoa and Australia's Super Rugby competitions.
The cross-hemisphere Rainbow Cup involving teams from Wales, Ireland, Scotland, Italy and South Africa starts on April 24.
(Reporting by Arvind Sriram in Bengaluru, editing by Ed Osmond)