As per BBC Sport, Jones was taken to hospital for x-rays on his shoulder after landing awkwardly following a midair collision.
The versatile player would have been almost a certainty for the World Cup squad for England, being capable of playing in central defence, at full-back or in central midfield, and Roy Hodgson and his coaches will be hoping the injury is not severe.
While other positions could be ably covered by other players, England face a headache at right-back in particular which Jones could have helped solve.
Phil Jones headed to hospital with a shoulder injury. Could be his World Cup right there. #MUFC— Jerrad Peters (@jerradpeters) May 6, 2014
If Phil Jones is out of the World Cup, then a begging bowl may go the way of John Terry. Or Rio Ferdinand. Or both.— John Brewin (@JohnBrewinESPN) May 6, 2014
Usual First Choices
Glen Johnson is England's established starter at right-back, having gained 50 caps in his international career to date. He will almost certainly be in place once the group stage of the World Cup gets underway.
The problem is, his domestic form has been alternating between average and horrendous for much of the season, with injury issues at intermittent periods and certainly not enough high-class performances to warrant him being the obvious choice for the position that he seems to be.
Kyle Walker, meanwhile, is almost certainly out of the World Cup after failing to recover from injury.
Go back a couple of years, and England looked fairly well stocked at right-back, especially with Micah Richards playing a big part in Manchester City's title-winning season of 2011-12. A powerful, athletic presence, who could defend as well as attack and be a presence in the air at both ends, Richards looked a natural successor to Johnson.
However, injuries and the excellent form of Pablo Zabaleta have firmly relegated him to a bit-part player for City, where he has played in just nine league games in the past two seasons combined.
Richards will likely leave in the summer and try to rebuild his career, whether that be at right-back or in the centre of defence, but he certainly won't be playing a part in Brazil.
With no Jones or Walker, Hodgson will have to get creative or get adventurous.
Chris Smalling is the only other defender in the regular squads who is capable of playing at full-back on that side, but he is far from ideal and certainly better suited to a central role.
Instead, Southampton's Nathaniel Clyne or Liverpool's Jon Flanagan might be looked at; Clyne is by far the more offensive-minded, dynamic option, while Flanagan is full of confidence after cementing a place in a side challenging for the league title this term.
Who should go as back-up right-back if Jones is out?
Both players are uncapped at the senior level and would represent risks of different kinds, but England might not be in the position to worry about such things. There is a very real chance that whoever travels as Johnson's back-up could be called upon to feature—both his form and fitness history suggest that.
Hodgson and Jones himself, of course, will hope the results show no lasting damage, but Clyne and Flanagan in particular might want to make sure they put in one final, big performance next weekend, just in case.