A lot of the backs have doubled up over the last two games
Gloucester centre Billy Twelvetrees has been handed a British and Irish Lions call-up because of injury concerns to the backline, according to the Rugby Football Union (RFU).
The 24-year-old, who can also play at flyhalf, has been with the England team in Argentina but will now leave South America for Australia, the RFU said in a statement.
Twelvetrees scored a try in last weekend's 32-3 win against the Pumas. The two sides play again in the second Test on Saturday.
The Lions currently have injury concerns over flyhalves Owen Farrell (dead leg) and Jonathan Sexton (hamstring). Centre Manu Tuilagi also suffered a stinger in the win over the Reds.
Twelvetrees has been capped five times for England and is the fourth player to receive a late call-up to the Lions for the tour against the Wallabies.
The Lions said in a separate statement that Twelvetrees would arrive in Sydney on Friday.
Head coach Warren Gatland said: "The nature of a Lions tour means that there will inevitably be knocks which take time to recover from.
"The whole squad have worked hard but a lot of the backs have doubled up over the last two games, either starting or from the bench.
"Billy played well in the first Test for England and he provides that versatility to cover a variety of positions."