Billy Vunipola is not guaranteed to start England's first test against Argentina on Saturday despite scoring a hat-trick in the Three Lions' 41-21 win against Consur XV.

Billy will join older brother Mako at Saracens next season and the 20-year-old younger sibling impressed against the South American select side on Sunday, putting down three times in six minutes.

England boss Stuart Lancaster however insists there are still many selection decisions to be made before he names his team on Thursday.

“Billy had a good game in terms of try scoring,” said Lancaster. “But I need to look at his contribution and those of all the others in the back row. 

"There are decisions to be made in the make-up of the back row and the bench.

"As you can see from the game, the breakdown will be fiercely contested on Saturday and there were times when we didn't deliver as good ball as we wanted.

"I have some decisions to make as to how we go about the game. The most important thing for me is it makes it clear how difficult it will be next Saturday.

"The sessions will be fiercely contested. We need to prepare well on Tuesday in order to get our mindset right for Saturday."

Fellow Men in Black players David Strettle and Richard Wigglesworth were also in action.