London - England prop Mako Vunipola has been ruled out of Saturday's international against Argentina with a knee injury, coach Stuart Lancaster said on Tuesday.
Vunipola started Saturday's 20-13 victory over Australia but was expected to drop to the bench against the Pumas following the return from a knee problem of British and Irish Lion Alex Corbisiero.
"Mako is unfortunately struggling with a ligament strain to his knee and is not available for selection this week," Lancaster said.
Meanwhile lock Geoff Parling has recovered from the mild concussion he suffered in training last week that ruled him out of the Wallabies match, so Dave Attwood was among 10 players sent back to their clubs on Tuesday.
Hooker Rob Webber is on standby for Saturday as Tom Youngs' wife is expecting their first child.
"There are a couple of changes to the squad with Geoff and Alex back and it's great they are back in the mix," Lancaster said.
"We have named an extended squad as we need a further 24 hours to assess one or two minor niggles in the build-up to the team announcement on Thursday morning."