SCOTLAND second row Gregor Brown has been called up to the British and Irish Lions’ tour of Australia amid concerns over the fitness of Joe McCarthy.

Brown joins Andy Farrell’s squad in Melbourne on Sunday to provide cover for Tuesday’s final midweek match against a First Nations and Pasifika XV, which is sandwiched by the first and second Tests.

McCarthy left the field in the 44th minute of Saturday’s 27-19 victory over the Wallabies because of a foot issue that makes him a doubt for the Lions’ shot at clinching the series in the looming rematch at Melbourne Cricket Ground (MCG).

“It was niggling away at Joe. We got him off. Hopefully we got him off in time,” said head coach Farrell, who revealed that the Ireland enforcer is struggling with plantar fasciitis.

Brown joins Rory Sutherland and Ewan Ashman in leaving Scotland’s tour of New Zealand to link up with the Lions. All three of them started Friday’s 41-12 victory over Samoa in Auckland.

The 24-year-old has won nine caps since making his debut against Canada last year and featured throughout the recent Six Nations.

Farrell is entering his most challenging week of the tour as he balances preparation for a potentially tricky fixture against the First Nations and Pasifika XV with the greater need of Saturday’s second Test.

By increasing the size of his squad to 45 players, he is attempting to prevent as few players as possible from backing up on Tuesday and Saturday while also ensuring his Test team are given an uninterrupted build up to the MCG showdown.

The Lions have won all six of their games Down Under so far and are determined to see their 100 per cent record maintained in Melbourne, but being confronted with a match at such a critical juncture of the tour presents all manner of headaches.

Farrell is embracing a fixture that was organised when original opponents Melbourne Rebels went into administration and even now refuses to separate his touring party into “dirt trackers” and the Test team.

“We care about the squad and nothing but the squad. That’s how it’s been the whole time. We’ve never separated once. We’ve been all in everything together,” Farrell said.

“We’ll name a side internally just before dinner on Sunday and then everyone will roll in on Monday to make sure that team, in an extended captain’s run like we’ve been doing over the past four of five weeks, has as good a preparation as we’ve had all tour. It matters to us on Tuesday night as a group.”

Finn Russell left the field early in the dominant victory at Suncorp Stadium but was suffering with cramp only.

Garry Ringrose (concussion), Mack Hansen (foot), Blair Kinghorn (knee) and Luke Cowan-Dickie (concussion) face fitness checks as they look to be involved in the penultimate week of the tour.