Matt Renshaw put on 52 runs with Shaun Marsh to keep the Indian attack temporarily at bay as runs came at a miserly rate.
Bangalore: Fighting half-centuries from Shaun Marsh and Matt Renshaw helped Australia secure a crucial first-innings lead over world number one India in the second Test in Bangalore on Sunday.
The visitors were 237 for six at stumps on the second day, leading India by 48 runs at the M Chinnaswamy Stadium. Matthew Wade on 25 and Mitchell Starc on 14 were at the crease.
Marsh top-scored with a 197-ball 66 before Indian seamer Umesh Yadav lured him into a tired-looking shot that was caught at short midwicket just before close of play.
Left-arm spinner Ravindra Jadeja claimed three wickets, including the key scalps of Australia skipper Steve Smith (8) and Renshaw (60) on a pitch that offered variable bounce.
Fast bowlers Ishant Sharma and Yadav, with a wicket each, unsettled the visiting batsmen but regular partnerships helped Australia surpass India's first-innings score of 189.
The visitors were faltering at the tea break on 163-5, but Marsh returned to score his sixth Test fifty while he and Wade put on 57 for the sixth wicket.
Marsh had his share of luck, surviving a few close calls against the Indian bowlers including nicking a Yadav delivery on 14 off the glove.
Earlier Renshaw, who started the day on 15, put on 52 runs with Marsh to keep the Indian attack temporarily at bay as runs came at a miserly rate of roughly two an over.
The left-handed opener, who had scored 68 in the first innings in Pune, looked ready to accelerate after hitting Jadeja for the first six of the match, but the bowler got his revenge two balls later.
Jadeja saw Renshaw emerge from his crease and fired the ball down the leg side as wicketkeeper Wriddhiman Saha completed the stumping in quick time.
Runs came at a trickle in the morning session, with the visitors scoring just 47 in 29 overs as two of their top batsmen Warner (33) and Smith were sent back to the pavilion.
Ashwin bowled Warner to get the opener for an eighth time in 12 Tests, while Smith battled hard for 52 deliveries before being caught by Saha off a wily Jadeja.
The morning was enlivened by banter between the lanky Sharma and Smith, who traded barbs as the day progressed.
The visitors lead the four-match series 1-0 after beating India in the first Test in Pune inside three days.