Sanchez, 36, the highest Argentina points scorer in international rugby with 902 points in 104 Tests, announced his retirement on his Instagram account.
Seventeen Wallabies have been named in the Reds squad travelling to England and Ireland to play two Super Rugby Pacific warm-up games against Bristol and Ulster.
New Fijian Drua head coach Glen Jackson has utilised traditional Fijian fondness for Sevens rugby as part of his side's preparation for Super Rugby Pacific this season.
New Zealand's Black Ferns Sevens are keen to be part of some Sevens history when the women's final of the HSBC SVNS tournament in Perth at the weekend will be played after the men's final.