Injuries to Henderson and Beirne give Ireland a Six Nations headache that will test strength in depth
Joe Schmidt warned that the weekend's action might bring about a change or two to his Six Nations squad and he won't have been happy to have been proved right once again.
To lose Tadhg Beirne and Iain Henderson for the first couple of games of the Championship will test the depth of Ireland's resources in the second-row.
As he jetted off to the Algarve yesterday, the coach will have been concerned by his dwindling options.
He can still start Leinster pair James Ryan and Devin Toner against England but below that his options are not as strong as they looked when he named his panel last Wednesday.
Ultan Dillane was included in the initial squad last week and he has been joined by his Connacht colleague Quinn Roux.
The Tralee native last played for Ireland against Fiji in November 2017 and has not been in the squad for a year, while Roux has been a consistent presence in the wider panel without ever earning a regular slot in the match-day squad.
Since his debut against his native South Africa in 2016, he has started three games against the United States, Japan and Italy and come off the bench in four games against the Italians and Wales in the Six Nations, Australia on last year's summer tour and the US last November.
Both have been going well in a resurgent Connacht side, as has Gavin Thornbury who was name-checked by Schmidt last week, but they have not offered the same potent range of skills as the two men they are replacing.
Henderson had only just returned from a five-week lay-off due to a thumb problem for Saturday's 14-13 Champions Cup win at Leicester, and picked up a fresh injury in that Welford Road victory.
"Iain Henderson suffered a finger injury that is likely to keep him sidelined for several weeks," Ulster confirmed in a statement.
"This fresh injury is unrelated to his recently injured thumb."
British and Irish Lions lock Henderson's absence will be a clear blow to head coach Schmidt, especially off the back of in-form Munster second row Beirne's injury too.
Former Scarlets lock Beirne starred again as Munster bruised past Exeter 9-7 in Saturday's Champions Cup victory.
"Following a scan Tadhg Beirne has been ruled out of the opening two rounds of the 2019 Guinness Six Nations with a knee injury," the Irish Rugby Football Union (IRFU) confirmed in a statement.
"Connacht's Quinn Roux has been called into the squad."
Last season, Schmidt selected Henderson and Ryan for the Grand Slam decider against England with Toner offering real solidity off the bench, while Beirne came into the equation in Australia and played a key role in getting the series win over the line.
Toner has forced his way back into the starting XV because of the security he gives the team out of touch, while his partnership with the devastatingly effective Ryan is well established at provincial level.
Since a mixed November, Henderson has been excellent for Ulster and was their best player in their win over Leicester after returning from thumb surgery, while Beirne has arguably been the most in-form player in Irish rugby this season.
The Ulsterman was one of the stars of the Grand Slam season, his role as a ball-carrier in the build-up to Johnny Sexton's drop-goal cannot be understated and he has been developing his lineout calling.
With a bruising encounter expected against England, Schmidt may have planned to rotate his locks for the Scotland game in week two but now that seems less likely.
England have their own injury issues and won't shed any tears, but the Ireland supremo knows that he is one injury away from a real problem in the second-row.
Add that to the shortage of form and fitness at scrum-half, the fact Sexton hasn't played in almost a month and the need to get Rob Kearney and Jack McGrath game time with Leinster this Friday and you have a couple of headaches he won't appreciate.
These may be first world problems for the Six Nations champions, but they are problems nonetheless.
Schmidt's side rely on clean lineout possession to attack and even the All Blacks wobbled when they lost a couple of second-rows in Chicago in 2016.
Eddie Jones will have noted how Leicester put serious pressure on Rory Best's throw on Saturday and the Ireland captain wobbled. Maro Itoje and co will target that area.
Dillane and Roux are decent bench options who bring their own strengths; Dillane is a dynamic carrier who has improved his work in the tight and Roux is an excellent scrummager and brings huge physicality to the breakdown.
If Ryan and Toner stay fit, then Ireland should be fine.
Beirne may be back for the round three game against Italy, and Henderson could return for the final two games; a six-day turnaround between France at home and Wales away.
Schmidt will challenge Dillane and Roux to seize the opportunity and create a selection headache when they return.
That mantra has served him and Ireland well and, with the World Cup looming, this is an interesting challenge for the squad to cope with the loss of important players.