David Warner’s return to form was the icing on the cake as Australia thumped Sri Lanka by seven wickets on Thursday for their second successive victory at the Twenty20 World Cup. Chasing the only major global trophy to elude them, Australia restricted Sri Lanka to 154 for six at the Dubai International Stadium. When they returned, Warner, aided by some luck, made 65 as Australia chased down the target with three overs to spare to join Ashes rivals England as the only two teams in Group I with a perfect record. Aaron Finch, the Australia captain, won the toss and elected to field against the 2014 world champions, Sri Lanka. Pat Cummins dismissed opener Pathum Nissanka early, but Sri Lanka finished the six powerplay overs at 53 for one looking on course for a big total on a batting-friendly track. For Australia, Adam Zampa, who bowled 12 dot balls in his four overs to claim two for 12, and Mitchell Starc applied the brakes by claiming four wickets between them. Charith Asalanka’s unbeaten 80 in their Super 12 opener against Bangladesh had secured Sri Lanka’s thrilling victory on Sunday. The left-hander followed it up with an entertaining 35 before spinner Zampa cut short his stay. Kusal Perera also made 35 but he fell to Starc immediately after hitting the left-arm quick for a massive six. Avishka Fernando and Wanindu Hasaranga did not last long, but Bhanuka Rajapaksa provided some fireworks in his unbeaten 33. Rajapaksa hit Marcus Stoinis for two consecutive fours and followed it with a six, but Sri Lanka could not make the most of their strong powerplay display. Australia did even better in their first six overs, cruising to 63 for no loss. Finch made 37 before he and Glenn Maxwell, who could not justify his promotion in the batting order, fell in quick succession. Warner’s form had been a major concern for his team and the opener was on 18 when Perera dropped a regulation catch behind the stumps. It proved a costly mistake as the left-hander went on to complete his fifty and fell only with Australia’s victory in sight. Steve Smith, unbeaten on 28, manoeuvred the ball around with characteristic deftness to frustrate Sri Lanka.