Resuming on 60 with the team score reading 170/3, Smith showed no signs of relenting although he was troubled on a few occasions by Jofra Archer to continue his prolific run-scoring spree and bring up his third Ashes century in 160 balls by clipping Craig Overton off his pads for a couple of runs.
Smith raised his bat as his teammates from the dressing room applauded in a fashion which showed the inevitability of yet another landmark from this run-machine who returned to the team on the back of a concussion injury.
Skipper Tim Paine was batting with him on nine from 31 balls.
A light drizzle once again played spoilsport in the first session, but it was for a short while as the packed crowd at Old Trafford were treated to another Smith special.
Overnight batter Travis Head was the first wicket for England as Stuart Broad (3/47) trapped him in front.
Mathew Wade (16) played a poor shot to be caught at mid-on by England captain Joe Root. But Smith, at the other end, was batting at another level as he negotiated left-arm spinner Jack Leach's spinning deliveries well and showed superb technique against Broad and Overton to work his way through.
Brief scores: Australia 1st innings: 245/5 (Steve Smith 101 batting, Marnus Labuschagne 67, Stuart Broad 3/47)
( With inputs from IANS )