Stephen Ferris has been forced to withdraw from The British & Irish Lions squad due to injury.
Wales' Ryan Jones has been called up as a replacement for the Ulster back-rower, who has suffered medial ligament damage.
It is a huge blow for the Lions as they play the Sharks on Wednesday evening before counting down the days to the first test against South Africa.
Ferris was considered a serious contender for the number six jersey for that test match and did himself no harm by registering a fine performance in the recent win over the Golden Lions.
However, this is the end of the tour for the 23-year-old as he will require treatment on his knee if he is to be back to full fitness for the new season.
"Ryan Jones has been called up to replace Stephen Ferris who unfortunately sustained a knee injury during Monday afternoon's training," said Head Coach Ian McGeechan.
"He twisted his right knee in a training drill and following a medical assessment it was decided that he should undergo a scan to determine the extent of the injury.
"He had the scan on Tuesday morning that showed he had a grade two tear to his medial collateral ligament. This usually requires a four to six week recovery period and is severe enough to mean he will miss the rest of the tour.
"Therefore with six matches left on tour after Wednesday's match against the Sharks we believe we need to fly out a replacement as cover for the backrow."