"Tubby" has consistently called for Khawaja to be left out, saying his only natural fit in the side is an an opener; which can't happen with Warner and Finch there.
Earlier, Afghanistan won the toss and opted to bat first but had a poor start.
Afghanistan recovered from a disastrous start in their World Cup opener against defending champions Australia to post a fearless total of 207 in Bristol on Saturday.
Warner, passed fit for the game after overcoming a leg injury, was outgunned by captain Aaron Finch (66 from 49) in an opening stand of 96 but fought on to hit a 74-ball half century, the slowest of his career and one that was booed by a section of the Bristol crowd following his ball-tampering misdemeanour in Cape Town in March previous year.
Asked to bat first, the Lankans were bowled out for a paltry 136 in 29.2 overs.
Smith and David Warner were back in the Australian lineup for their first official one-day internationals since returning from 12-month bans for their part in a ball-tampering scandal in South Africa in March, 2018.
However, the boos and the harsh treatment which Warner and Smith received didn't have any effect on their batting as they shared together a 40-run stand to help Australia begin their title defence in an emphatic manner by registering a seven-wicket win over Afghanistan.
"We've done a lot of work in the nets over the last couple of weeks, but he missed one of the practice games with that little niggle he had, so it took him a little bit of time to get going", he added.
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He was also named the player of the match.
"Warner is very important to our side", said Finch.
Paceman Mitch Starc clean-bowled Mohammad Shahzad on the third ball and Pat Cummins had Hazratullah Zazai caught behind in the next over to make it 5-2.
"I think credit is due to Afghanistan as they came out and played some fearless cricket", said Zampa. But we're handling it really well at the moment'. Since then, Rahmat Shah and Hasmatullah Shahidi tried to bail the innings adding a 51-run partnership. Rahmat Shah and Mohammad Nabi followed as Afghanistan were struggling at 77/5 in 21st over. Naib's wicket started a collapse as Afghanistan lost the wickets of Najibullah Zadran and Dawlat Zadran in quick succession. Najibullah Zadran (51) and Naib (31) joined forces at 77-5 and upped the tempo in an 83-run stand, belting Zampa out of the attack by clouting two boundaries and two sixes off the last four balls of the 29th over.
Najibullah's half-century came off just 46 balls, with seven fours and two sixes, before Rashid Khan took up the mantle at number eight with two fours and three sixes in his 27.
Afghanistan captain Gulbadin Naib: "Playing against this kind of team we can learn lessons".
"We will take some positive thinking", said Zadran.