Smith’s 138 not out powered Australia to an imposing first innings total of 492 for nine declared on the second day as they sought a consolation win after England had already taken the series at 3-0 up.
When bad light ended play for the day, England were 32 without loss, a deficit of 460 runs. England captain Alastair Cook was 17 not out and Joe Root 13 not out.
For Smith, a first hundred in his 12-Test career was all the more welcome as he’d fallen 11 runs short during the drawn third Ashes match in Manchester.
But he achieved the coveted landmark in style Thursday with an on-driven six off occasional medium-pacer Jonathan Trott.
“I was a bit nervous after getting out for 89 at Old Trafford but I had a chat with Hads [Brad Haddin] and said with Trotty bowling I thought I’d give it a go,” Smith told BBC Radio’s Test Match Special.
“I’m very happy to get the hundred under my belt, I feel like my game’s going OK at the moment, I’m probably leaving the ball better than I have done before.
“The pitch is still pretty good, while the ball is still hard it will be important to take a few wickets in the morning,” he added.
Smith was 66 not out and nightwatchman Peter Siddle 18 not out following Shane Watson’s Test-best 176 on Wednesday.
Smith, whose previous Test-best was the 92 he made against India in Mohali in March, batted for more than six-and-a-half hours and faced 241 balls with 16 fours and two sixes.