Davids suffered a groin injury at the HSBC New Zealand Sevens last weekend and was ruled out of the tournament at the Allianz Stadium, where South Africa will meet Kenya on Friday and Uruguay and New Zealand on Saturday in Pool B of the tournament.
Murphy is no stranger to the Blitzboks and made his 12th tournament appearance in Cape Town in December, where he played the last of his 52 games in a Springbok Sevens shirt. He has not played in Australia before though, and will make his debut at the Sydney venue.
He was keen to jump on the plane to Sydney, despite having just starting a safari with his family.
“I was the 14th player for the trip and when the rest of the training squad were given some days off, I could join the family in the Kruger National Park,” Murphy said from Sydney.
“But I did pack a bag with my rugby stuff just in case I got the call, and that is exactly what happened.
“I started Sunday morning with a sunrise game drive and when I had reception again, I saw the message from coach Philip (Snyman) asking me to join them. It is never nice to replace an injured teammate, so I felt for Selvyn, but I am ready to go and contribute and answer the call of duty.
“The guys from the SA Sevens ‘A’ squad put in some heavy sessions at Stellenbosch last week, so I am well prepared.
“The call-up certainly made up for the original disappointment I felt having missed out. I am looking to be a more regular option in the starting team and this gives me a great opportunity to contribute and show the coaches the growth in the areas they wanted me to improve on. So yes, I am missing out on some fabulous wild life in the Kruger, but I want to contribute to this amazing team, so it is a no brainer for me.”