While Jason Roy left the field feeling tightness in his left hamstring, Morgan is struggling with a back spasm AFP

The next 48 hours will be the most important of England's World Cup as they await updates on the fitness of both their captain Eoin Morgan and their star opener Jason Roy.

Both batsmen went down in the first innings of the host's fourth match of the tournament against West Indies. Thankfully, the team held it together in comprehensive fashion, restricting West Indies to 212 and then knocking the runs off in leisurely fashion off 33.1 overs for the loss of just two wickets.

Roy was the first to fall. A chase of a ball skewed over the covers saw him pull up and turn towards the balcony during the eighth over of the match. He was feeling his left hamstring as he walked off and, soon, the ECB confirmed he needed further assessment after "feeling tightness".

During the 40th over, Morgan doubled over and had to be helped from the field. Such was his discomfort, he stopped on his way to the changing room after finding the stairs up to the dressing room particularly difficult to conquer. Both players will undergo scans tomorrow to survey the damage.

It seems Roy is the greater cause for concern. It's worth remembering two things: firstly that the 28-year old missed the start of the county season with Surrey because of an issue to the same hamstring. He was only able to play two List A matches for his club and was deemed unfit for the county's four-day matches before joining up with England for the ODI series against Pakistan.

Secondly, it is worth noting the word "tightness": the last time it was used to describe Roy's left hamstring, back in February in the Caribbean, he ended up missing the last two ODIs and the entire three-match T20I series. Along with, of course, those games for Surrey.

Morgan, standing for the duration of his post-match press conference because sitting down would be too painful, said England "were not at panic stations yet". While he urged a degree of calm, he did say the weekend would bring more news, good or bad.

"I've had back spasms before," said Morgan, referencing the one he had last June on the morning of the second ODI against Australia. He played in the third, just two days later. This latest spasm, though, is in a different area. "You normally get a good indication the following day. If it settles down a little bit, the improvement is there straight away, and the following day is better."

"He [Roy] is going for a scan tomorrow and it will probably take 48 hours before we have the results."

England's next match is against Afghanistan in Manchester on Tuesday before they travel to Leeds to take on Sri Lanka on Friday. Though two of the weakest sides in the competition, these issues, combined with the short turnaround, have tempered whatever ease there might have been.

Though Jos Buttler deputised capably as vice-captain, losing Morgan would leave England without the cool head that led them to the top of the ODI rankings and into this competition as favourites.

In Roy's absence, Joe Root opened up and hit his second hundred of the World Cup and carrying his bat to take England to their target of 213. However, the Surrey batsman is the world's form white-ball opener, with over 1,511 ODI runs and six hundreds - at an average strike rate of 110 - since the start of 2018. It's not simply how many he scores, but how he scores them: taking bowlers out of the attack with a gung-ho approach and a selection of shots that, at times, make it impossible to set fields to him.