Dawson, who has been in the XI for the opening two matches, sat out training on Monday, ahead of the third one-day international against Sri Lanka in Pallekele. After the injury was assessed by medical staff, the decision was taken to send him home, with PCA Players' Player of the Year Denly coming out to Sri Lanka early.
Denly has been preparing for his return to the England set-up after more than eight years, having been selected for the Test party following two impressive seasons with Kent in which his batting has been rejuvenated and his legspin a surprise success across the formats. He will arrive in Pallekele on Wednesday, hours before the third ODI, and could at some stage win his first one-day cap since the 2009 Champions Trophy.
England have fielded three frontline spinners at the start of the series - Dawson joining Moeen Ali and Adil Rashid in the side - so unless Denly steps off the plane and straight into the side, it will likely mean a different balance and the chance for one of the other seamers to come into the team. Joe Root's offspin could help cover for Dawson's absence if required.
Mark Wood, Tom Curran and Sam Curran have been carrying the drinks so far after England opted for a spin-heavy attack and also preferred Olly Stone to share the new ball with Chris Woakes.
Dawson claimed one wicket in England's victory in Dambulla, hustling through the overs alongside Moeen to ensure the 20-over mark was reached before rain arrived, meaning the result would stand without needing the reserve day. Early wickets for Woakes and Stone, during an impressive first spell at international level, had left Sri Lanka well behind the DLS target.
A surprise visitor to training this morning... pic.twitter.com/ETdHFMuQ2x— England Cricket (@englandcricket) October 15, 2018
There was an extra visitor to England's training session on Tuesday when a cobra was spotted by groundstaff behind the pavilion. It was removed with the help of a drain pipe and a sack. England's players had spent some of their downtime in Dambulla getting up close with local wildlife around their hotel and on safari - some posted on Instagram holding a python - but it's unlikely many would be volunteering to get too close on this occasion.
It isn't the first time, however, that England's cricketers have encountered snakes in Sri Lanka. On the 2007 tour, two were spotted on the boundary's edge during a warm-up match in Colombo. Matthew Hoggard was among the players keen for a closer look that day.
*6PM BST - This story was updated with news of Denly replacing Dawson