Ireland's defeat to South Africa may well have come at a major cost with fears that Dan Sheehan has suffered a torn anterior cruciate ligament.
The hooker picked up the injury 27 minutes into Saturday's 27-20 defeat to the world champions, after jarring his left knee while tackling second row Eben Etzebeth, and while he initially played on until half-time after getting the knee strapped, he was replaced at the break by Rónan Kelleher.
For the opening ten minutes of the second half, Sheehan could be seen pitchside at Loftus Versfeld testing out the injury on a stationary bike, while head coach Andy Farrell said the 25-year-old would be a doubt for next Saturday's second Test in Durban.
However, the damage now appears to be more serious than first feared, and Sheehan left the Irish camp before they departed Johannesburg on Sunday.
If the suspected ACL injury is confirmed, it could rule Sheehan out until well into next season, and he would be a real doubt to feature in the 2025 Six Nations.
The Leinster hooker (below) has established himself as one of the best in the world in his position, cementing himself as first choice for province and country and winning World Rugby's Breakthrough Player of the Year in 2022.
This season, he's been nominated for both the Rugby Players Ireland and Investec Champions Cup Player of the Year awards, while in April he was promoted to a central contract with the IRFU, illustrating how important he has become to Farrell's plans.
Kelleher is now likely to step up into the starting role for this weekend's second Test, with Ulster's Rob Herring joining the matchday squad. As of now, it doesn't appear that a replacement will be rushed in to join the squad at their base in uMhlanga, just north of Durban.
Meanwhile, there aren't expected to be any citings coming from Saturday's first Test.
Ireland's management are understood to be unhappy after the tackle by RG Snyman, which left Craig Casey with a severe concussion and almost certain to miss this weekend's game, was left unpunished by referee Luke Pearce and his TMO Ben Whitehouse.
Snyman initially grabbed the arm of his former Munster team-mate, which led to a knock-on by Casey. However, it's believed the Irish frustration stems from the follow up tackle which occurred off the ball, and resulted in the scrum-half hitting his head off the ground, which left him unconscious.
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