Supporters were left surprised when Cucurella did not reappear for the second half, particularly given his influence in the opening 45 minutes.
While not quite at his absolute best, the left-back played a key role in Chelsea's early control, providing width and balance down the flank with a series of overlapping runs that stretched the Leeds defence. Nothing in his performance appeared to suggest that a half-time substitution was necessary.
Jorrel Hato emerged immediately after the restart in place of Cucurella, prompting initial speculation that the defender had suffered an injury. Those suspicions were later confirmed by manager Liam Rosenior in his post-match interview.
Rosenior revealed that Cucurella had sustained a hamstring injury during the first half against Leeds. The precise severity of the issue was not disclosed, leaving fans anxiously awaiting further updates from the club's medical staff.
"He felt his hamstring at half-time, which is why we made the change for Jorrel," said Rosenior.
"Jorrel came on and played very, very well, but hopefully it's not too serious. It was a substitution for an injury."
The timing is far from ideal, with Chelsea scheduled to face Burnley in their next Premier League fixture at Stamford Bridge in 10 days' time.
The break before that encounter may offer Cucurella a chance to recover, and there is hope he could still be available to start.