England and Lions loosehead prop Mako Vunipola has been ruled out for the entirety of the 2018 Autumn International period, with Saracens confirming that the 27-year-old will require extensive rehabilitation for a calf strain sustained during the London side's Champions Cup victory over Glasgow Warriors last Sunday.
Vunipola's Saracens and England teammate Nick Isiekwe has also been ruled out of any chance of recovering in time for England's November Tests, having suffered ankle injury at Scotstoun.
Saracens have given Vunipola an expected six week recovery period, while Isiekwe will require eight weeks away from the game.
This unwelcome news comes following the revelation earlier this week that talismanic number eight Billy Vunipola has suffered a third fractured forearm. The barnstorming backrower has been given an estimated three month recovery period.