Gloucestershire 116 for 4 (Hammond 59, Roland-Jones 3-29) trail Middlesex 445 for 9 dec (du Plooy 182, Cracknell 97) by 329 runs
However, youngster Naavya Sharma had Price caught at square leg in the last over of the day to leave the hosts in charge.
Middlesex resumed on 279 for 5 with du Plooy two runs short of a century and the Seaxes’ skipper duly reached the landmark inside two overs with a single to midwicket.
Cracknell got rolling with two quick boundaries to raise the hundred stand before du Plooy crunched one through the covers to bring up the 300.
There was a scare for du Plooy on 110 when a leading edge fell just short of a diving Craig Miles at cover, the seamer leaving the field briefly in the aftermath of the incident.
With that close shave behind him du Plooy became the aggressor of the partnership, square driving for four, before welcoming Miles back onto the field by planting him over point for six.
Du Plooy moved to 150 while Cracknell got to within three of a century only to be undone by the spin of Graeme van Buuren who turned a full ball between bat and pad to hit the stumps and leave the wicketkeeper-batter crestfallen.
Zafar Gohar contributed 26, but du Plooy was becalmed after lunch before falling to the first ball of occasional spin from Hammond – a delivery which went through his legs to hit middle stump.
Not content with that, Hammond claimed another in his solitary over trapping Roland-Jones lbw and the declaration soon followed.
Gloucestershire skipper Cameron Bancroft and fellow opener Ben Charlesworth began solidly enough before Roland-Jones, charging in from the Pavilion End conjured up his latest spell of seam-bowling wizardry.
The 38-year-old former England man set Bancroft up with one which beat the outside edge, before bringing one back the other way to slip past the bat and clip the off stump.
Six balls later, Roland Jones disturbed timber again, though this time Charlesworth contributed to his own downfall with a lack of foot movement and loose drive that deflected onto the stumps from the bottom edge.
The wicket allowed Gloucestershire to seek the sanctuary of the pavilion for the tea interval but when they emerged Roland-Jones inflicted further scarring with almost a carbon copy of the ball which snared Bancroft, Joe Phillips getting an inside edge before hearing the dreaded death rattle.
It was left to Hammond to steady the ship and with the ball finally out of Roland-Jones’ hand he found a brace of boundaries off some loose offerings from Sharma.
The 30-year-old left hander might have perished sweeping at Gohar only for Sebastian Morgan to misjudge the flight of the ball in the gloom and it slipped away for four.
Scare survived and with the sun having returned, Hammond moved to his half-century complete with seven fours but Price’s late demise left Middlesex in good heart at the close.
