Steven Smith century takes Australia to 420/4 at lunch on Day 2

Striking his fourth century of the series, captain Steven Smith helped Australia reach 420 for four at lunch on the second day of the final Test against India at the SCG on Monday.

Resuming the day on 348 for two, the hosts found it tough to get runs against a disciplined Indian attack but overnight batsmen Smith (117) and Shane Watson (81) stitched together a 196-run third-wicket partnership to keep the fight on.

The Virat Kohli-led India though did seem to learn its lessons from day one as the visitors only conceded 72 runs in the 30 overs bowled in the morning session and also got two 'set' batsmen back in the pavilion.

Watson was the first to go, adding just 20 more runs to his overnight score, as Mohammed Shami (2-80) got his second wicket of the innings so far.

Watson was guilty of throwing away a Test hundred after he forced a pull of a short ball only to pick the fielder at deep mid-wicket.

Smith departed six overs later as the in-form batsman was also guilty of chasing a wide Umesh Yadav (1-119) delivery only get a feather touch and it was a regulation catch for wicketkeeper Wriddhiman Saha. But Smith sure showed his class in his 208-ball stay at the crease as the batsman mixed the right dose of caution and aggression, his innings laced with 15 fours.

India though could have got another wicket in the 115th over of the innings through Ravichandran Ashwin (1-98) after the off-spinner forced Shaun Marsh (14 not out) to edge one to gully only to see a diving Murali Vijay drop the red cherry.

Joe Burns, who joined Marsh after Smith's fall, has had a torrid time in the middle and is yet to open his account after facing 17 deliveries.