India, Nov. 22 -- Usman Khawaja's absence from Australia's opening partnership on day one in Perth was neither tactical nor related to his form. It was the product of back spasms, medical treatment, and a strict timing regulation that converged precisely at the wrong moment.

Khawaja spent time off the field late in England's innings receiving treatment for back spasms. Under cricket's substitution laws, any player who leaves the field must complete an equivalent period back on it before becoming eligible to bat. England's lower-order collapse unfolded while Khawaja was still technically off the field, and the innings concluded before he had fulfilled his required time.

The result: Australia's most experienced opener was ruled ineligible...