Jacobsen, 28, was carried off on a stretcher during Scotland's opening 56-10 win over Portugal in St Etienne.

The Scotland camp confirmed this afternoon that the Edinburgh forward would miss the rest of the tournament.

Jacobsen will be replaced by Alasdair Dickinson, who has received an unexpected birthday present with his call-up.

The uncapped Gloucester player, who turns 24 on Tuesday, will fly into Lyon tonight before meeting up with the rest of the squad.

And Scotland coach Frank Hadden feels Dickinson can soften the blow of Jacobsen's loss.

Hadden said: “It's clearly a disappointment to lose 'Chunk'.

“He worked incredibly hard over the summer and was in great shape.

“However, Ally was also part of our preparation squad so he is very much up to speed with what we do and he has worked assiduously on his development as a player.”

Dickinson, who has been involved in one of Gloucester’s pre-season games, said: “I’m delighted to be called up, but obviously I feel a bit for 'Chunk' because he’s a good mate from my days with Edinburgh.”

Scotland team doctor James Robson explained Jacobsen had suffered a tear to his left calf muscle which will keep him sidelined for six to eight weeks.

He also reported that a number of players would miss training for part of this week as a result of injuries sustained during the eight-try win over Portugal.

Lock Nathan Hines (ankle and knee bruising), wing Sean Lamont (ankle), flanker Allister Hogg (dead leg) and full-back Rory Lamont (shoulder) will all receive treatment from the Scotland medical team.

Centre Andy Henderson continues to make “slow progress” following the dead leg he suffered in last month’s warm-up against South Africa.