Cape Town - World Rugby has announced an amendment to Law 3 to stipulate that a match cannot restart until a player leaving the field of play for a blood injury or Head Injury Assessment (HIA) has been temporarily replaced.
This follows Wales winger George North's try against England in Cardiff last weekend. North dotted down for a crucial score in Wales' 13-6 victory when the visitors had just 13 men on the park.
England's Anthony Watson was off with a yellow card, while at the same time scrumhalf Willi Heinz had to leave the field for an HIA.
After receiving a penalty, Wales flyhalf Dan Biggar took a quick tap before England could bring on a replacement for Heinz, with North eventually rounding off after a cross-kick.
World Rugby posted on its official website that the amendment, approved by the international federation's executive committee, codifies an area that was previously at the discretion of the referee.
"It has the dual intention of promoting player welfare best practice by enabling a player to be assessed and treated as soon as possible, while also ensuring that teams are not disadvantaged by playing with fewer players than permitted for a short period," a statement from the governing body read.
Wales' victory also saw them surge to the top of the World Rugby rankings for the first time.
Top 20 in the latest World Rugby rankings:
1. Wales 89.43
2. New Zealand 89.40
3. Ireland 88.69
4. South Africa 86.83
5. England 86.79
6. Australia 84.05
7. France 80.58
8. Scotland 79.01
9. Japan 77.21
10. Fiji 76.98
11. Argentina 76.29
12. Georgia 74.42
13. Italy 72.04
14. USA 71.93
15. Tonga 71.49
16. Samoa 69.08
17. Spain 68.15
18. Romania 66.69
19. Uruguay 65.18
20. Russia 64.81
Others:
23. Namibia 61.01
32. Kenya 51.44
33. Zimbabwe 51.42