Somerset 94 for 4 for trail Warwickshire 413 (Trott 175, Ambrose 63, Clarke 57) by 319 runs
A Jonathan Trott century has earned Warwickshire an outside chance of victory in the bottom of the table battle at Taunton.
Trott made 175 - the 20th score of 150 or more in his first-class career - to help Warwickshire to their highest first-innings score of the season. It was his second century of the Championship campaign and his third of the first-class season.
Grant Thornton, a debutant seamer recently signed on a three-month contract, then claimed wickets with his eighth and 23rd deliveries in first-class cricket to build pressure on Somerset. Realistically, they require 264 to avert the follow-on and make the game safe on the final day.
Perhaps, had Trott been caught at gully before he had added to his overnight 50, Somerset may have taken control of the match. But the chance, an outside edge from a Craig Overton delivery, was put down by Peter Trego and Trott added 146 for the fifth-wicket with Tim Ambrose - Warwickshire's highest Championship stand of the season - to steer Warwickshire into the ascendancy.
Somerset had worked hard for that chance. Trott had gone scoreless for the first 20 minutes of the third day and survived a sustained appeal for a catch down the leg side. He was also fortunate to escape a top-edged slog-sweep off Jack Leach when he had 55 that flew just over the head of Marcus Trescothick at slip.
From then on, however, he began to take control. Leach, who conceded only three boundaries in his first 20 overs, was taken for five fours in seven balls at one stage while Trott hit three sixes - he admitted he couldn't recall hitting more in a first-class innings - including a slog-sweep off Roelof van der Merwe to bring up his century and a thundering drive into the Sir Ian Botham Stand off Jamie Overton. Having suffered three ducks in the Championship this season, he was determined to take advantage of his start. It was the 42nd first-class century of his career and he passed 17,000 first-class runs in its latter stages.
Despite the acceleration, Warwickshire missed out on full batting bonus points. Requiring eight runs off the final over of the 110-over qualifying period, they fell five short despite Rikki Clarke's aggressive 50 (from 53 balls). Still, this was the first time this season they had recorded even four batting bonus points in an innings and represented a step in the right direction after a poor start to the season.
Warwickshire lost their last five wickets for 22 in an attempt to up the pace. Van der Merwe finished with three wickets and probably gained a little more turn than Leach, but Jamie Overton remained the pick of the bowlers. Gaining movement in the air and off the surface, he generally maintained a good, probing length.
The value of Trott's innings soon become apparent as Somerset subsided to 86 for four against an attack containing two Championship debutants. Tom Abell's grim run of form - he has now scored 10 runs in five Championship innings this season and starting to worry those who feared the captaincy was offered to him prematurely - continued as he defended a delivery from Jeetan Patel only to see it dribble back off his bat and knock off the bails, before Steve Davies (34 runs in five innings) turned one off his hips only to find Sam Hain, at short-leg, able to cling on to a very sharp chance.
That was Thornton's second wicket. Bowling at an odd angle amid a whirl of arms, he represents an awkward proposition for batsmen who have not seen him before and appeared to surprise James Hildreth with a full ball that found the batsmen crease-bound and perhaps playing slightly across a straight one. Dean Elgar, beaten by a couple that left him sharply, was leg before to one that didn't swing.
Had Leach, the nightwatchman, been taken at slip - as he might have been as he twice edged Patel agonisingly close to the cordon - Somerset would have been in deep trouble. But Trescothick, not for the first time, ensured some stability. Resuming on the final day nine runs short of reaching 50 for the 186th time in first-class cricket, he passed 25,000 first-class runs late on the third evening and, aged 41, remains the wicket that opposition most value in this Somerset side. He knows he has work ahead of him on the final day and he will relish it.
"I've been sweating on that record for a couple of weeks," he said afterwards "I knew I needed to reach 29. I remember my first run: it was 1993 and I made 1 and 3 in a game against Lancashire. I reckon my first run was down to third man. And I've scored a fair few more down there over the years."
Earlier in the day he pulled off an outstanding catch to dismiss Ambrose. Seeing the batsman shape for a delicate sweep, he ran from slip to leg slip and dived full length to cling on to a well-anticipated chance.
"There is no chance I will be still be playing at 41," 36-year-old Trott said later. "That's just silly!
"It's great that Marcus is still playing county cricket and setting an example to the young players in his dressing room and opposition teams. His will be a huge wicket for us tomorrow."
Meanwhile it is understood that interviews for the role of chief executive at Somerset have begun. ESPNcricinfo understands that, of the 125 applicants, Jason Ratcliffe, Charlie Hodgson and Jez Curwin are among the short-listed candidates. Hodgson is the commercial director at Surrey, while Curwin fulfils a similar role at Somerset. Ratcliffe was a player at Warwickshire and Surrey before moving to the PCA where he spent 14 years, latterly as deputy chief executive.