Khawaja, who struggled against England's second string bowlers gets the call to replace Clarke - if neccessary. Why was Steven Smith originally in the squad? The guy performed last week with the bat, he could easily slot into fourth.
Obviously Smith won't be selected for the first test.
Another mistake from the selectors and if Clarke doesn't play, I'm unloading on England to win the first test and the series because Khawaja will not score big at all.