The very reason Jordi Murphy moved to Ulster could be in jeopardy, at least for November.
The 27-year-old flanker is a long-time favourite of Ireland coach Joe Schmidt.
It is not for his explosive power, but for his attention to detail.
Murphy is a dedicated member of the 'do your job' club and is an all-rounder with better lineout agility than any other Ireland back rower besides Peter O'Mahony.
He has been part of many of Schmidt's big-game plans, playing notable roles against the All Blacks in Chicago and Argentina in the 2015 World Cup.
There was also the involvement in the Grand Slam decider against England and the two starts from the three tests in Australia this summer.
There are just two barriers between Murphy and his ambition to make it to the 2019 Rugby World Cup.
The first is the regular first-team game time which could not be guaranteed at his home province.
The presence of Sean O'Brien, Dan Leavy, Rhys Ruddock, Josh van der Flier, Jack Conan and even Scott Fardy gave Leinster coach Leo Cullen an overload of international options in the back row.
Thus, Murphy made the decision to take the M1 from Dublin to Belfast in order to realise his playing ambition and, presumably, for the nice bonus of a pay hike.
The second barrier for Murphy is the dread of injury.
Sure enough, the release of Ulster's injury information from the weekend revealed how Murphy "sustained an ankle ligament injury against Edinburgh and he won't be fit for the upcoming fixture against the (Southern) Kings."
The worry is that it did not come with a timeline for his return to action. Now, this may mean nothing or it could mean everything.
Assistant coach Dwayne Peel had already indicated Murphy would not be available for The Cheetahs the following week.
It comes soon after Munster refused to give any estimate about Conor Murray's return from a neck injury.
There does seem to be a trend towards keeping the release of injury information to a minimum.
There was better news for Ulster with the confirmation that tight-head Tom O'Toole and loose forwards Jean Deysel and Clive Ross are available for the flight to South Africa.
Chris Henry has been ruled out by a calf strain and Alex Thompson has a similar problem in need of resolution.
In the week after the announcement of Dominic Ryan's retirement due to concussion, Ulster second-row Peter Browne and wing Jack Owens have entered into the return-to-play protocols from concussive episodes playing against Leinster A in the Celtic Cup last Friday.