CREATE TABLE table_74142 ("Date" TEXT, "Player" TEXT, "Injury" TEXT, "Date of injury" TEXT, "Number of matches  ( Total ) " TEXT, "Source" TEXT)

What is the date of injury when the injury is sustained posterior thigh strains in his left leg?
SELECT "Date of injury" FROM table_74142 WHERE "Injury" = 'Sustained posterior thigh strains in his left leg'
SELECT "Date of injury" FROM "table_74142" WHERE "Injury" = 'Sustained posterior thigh strains in his left leg'