Warner also spoke about his gesture of finger on the lips after reaching a superlative ton.
Pat Cummins won the toss and chose to bat first and openers Warner and Khawaja (41) posted 126 runs for the opening wicket.
It was David Warner, who looked determined to make an impact with the bat as there were questions raised over his inclusion in the Test squad and him wanting a perfect farewell in Sydney after the third and final Test match of the series.
Notably, Warner's former teammate, Mitchell Johnson, questioned the Australian opener's form and questioned whether the top batter deserved a hero's send-off. Johnson raised concerns about Warner's recent troubles in the lengthier format, as well as his involvement in the 2018 ball-tampering scandal.
Warner brought up his century in 125 balls and celebrated in his trademark way with a jump in the air and chest thump. In a unique gesture during the celebration, he placed his fingers on his lips, casting a glance upwards.
“It’s my job to come here and score runs. It was good to get a couple of partnerships, first with Uzzie (Khawaja) and then with Smudge (Smith). (On his century) It does feel great, it’s about putting runs on the board for the bowlers. No better way to silence the critics than by putting runs on the board,” Warner told broadcasters during the tea break as quoted by Cricbuzz.
During a conversation with former Australia opener Adam Gilchrist after the conclusion of the second session, Warner clarified that his gesture was merely a reaction to the criticism about his position in the team leading up to the Test.
"It was just another Test hundred for Australia. Always feels great. We need to put enough runs on the board to give the bowlers something to bowl at. Yeah, if put in the right areas, the wicket looks a nice one. You can do nothing about the criticism, but you have to put your head down and get into your work. Nothing better than getting runs and silencing the critics," Warner added.