Gloucestershire 165 and 373 for 5 (Harris 148, Hammond ) lead Glamorgan 404 (Root 117*, T Price 4-56) by 134 runs
Harris didn't make any mis-steps on his way to his fourth first-class hundred for Gloucestershire. In the first innings he made 59 but in testing conditions he didn't hit the ball to the boundary until the 92nd ball he faced. In the second innings he was markedly more expansive and reached his hundred with his 16th boundary from his 131st delivery.
Starting their second innings 239 runs behind Glamorgan, a redoubtable display with the bat was essential, and the hundred from Harris and fifties from Chris Dent and Miles Hammond gave them hope of getting something out of a game that remains in the balance.
Glamorgan struggled to find the control that they had shown in the first innings of this game on a pitch that appears to be flattening out as the match progresses. When bad light brought the day to a close Gloucestershire had reached 373 for 5, 134 runs in front.
Glamorgan began the day on 388 for eight, 223 runs in front of Gloucestershire. They had added just 16 more runs when their last wicket fell with Joe Root not out on 117. This still represented a sizeable lead, and they would have been hopeful of making inroads in the morning session.
That wasn't to be, with Harris and Chris Dent progressing serenely on a pitch that has changed markedly from an opening day where batting demanded great care.
There was clear intent from the Gloucestershire openers who made a large dent in Glamorgan's lead in the opening session of day three. The fifty stand between Dent and Harris look just 53 balls and they had reached 133 without loss at the lunch break.
It looked as if the opening pair would surpass Gloucestershire's first innings effort of 165 but they came up just short. Dent chopped a ball from Timm van der Gugten onto his stumps when he was on 78 to leave Gloucestershire at 161 for one. They erased the first-innings deficit for the loss of just two wickets with Miles Hammond and Harris sharing a partnership of 111 either side of the tea break.
Harris was dismissed when he attempted to reserve sweep a Kiran Carlson yorker and was trapped lbw, with Hammond departing 12 runs later when he missed a pull shot and was bowled by Dan Douthwaite.
With Australia set to play the World Test Championship and the Ashes in England this summer this was a reminder of what Harris is capable of. Squads have yet to be selected, but with Harris already rewarded with an Australian central contract he is clearly in the selectors' minds.