Brilliant Ben Coad gave Yorkshire hope of a fightback against Glamorgan with three evening wickets after more frustration during the early stages of day two at Emerald Headingley.
At tea, the Welsh side had claimed a first-innings lead of 137 in this opening round LV= Insurance County Championship fixture, with Yorkshire all out for 193 in reply to 330.
But Coad struck three times with the new ball, adding to four wickets in the first innings, to change the momentum of the Group Three contest as Glamorgan fell to 29-4.
The visitors later closed a 16-wicket day on 68-4 from 29 overs, leading by 205.
Billy Root and Chris Cooke ensured there was no further damage and will begin day three on 25 and 17 respectively.
Yorkshire lost England Test captain Joe Root for a uncomfortable 16 as they slipped to 175-9 and only just reached the 181 follow-on target shortly before tea.
Dom Bess batted impressively for 38 not out to help them achieve that milestone after Adam Lyth made 52 and Harry Brook 40.
Having let the visitors off the hook from 29-3 and 132-7 on day one, the White Rose were unable to claw things back with the bat as the wickets were shared around the Glamorgan attack.
Off-spinner Callum Taylor, who claimed the wicket of Root, struck twice, as did Australian Michael Hogan and fellow seamers Dan Douthwaite and David Lloyd.
Glamorgan started day two on 310-8 in their first innings, and 39-year-old Hogan was at the heart of the morning action with runs and then wickets.
He moved from 40 to 52 with three boundaries in the first over of the day, bowled by Coad, who finished with 4-94 from 26 overs.
Coad then got his man for 54 caught by Steve Patterson, running back from mid-off.
Patterson later wrapped up the Glamorgan innings by trapping Jamie McIlroy lbw. Timm van der Gugten finished unbeaten on 85.
Hogan then had Tom Kohler-Cadmore caught behind for 11 and bowled Tom Loten for a duck as Yorkshire slipped to 31-2 inside seven overs.
Billy Root then almost had brother Joe lbw sweeping on four with his part-time off-spin, though Joe was adjudged to have got himself outside of the line.
Yorkshire’s Test skipper, however, was soon to encounter more problems in a 59-ball innings which belied his excellent winter form in Sri Lanka and India, including back-to-back double centuries.
Lyth and Root took Yorkshire to lunch at 65-2 under overcast skies.
Unfortunately, following a two-minute period of silence at the start of the afternoon to mark the passing of HRH Prince Philip, they quickly slipped to 79-4, losing both batsmen.
Lyth was lbw to Douthwaite and Root caught at mid-off having miscued a full toss from Taylor (79-4).
Normally, Root, who had also offered the same bowler a sharp return chance on 12, would have dispatched it for six into the Emerald Stand. Instead, it caught the toe of the bat and went high and not handsome.
The pair were two of eight afternoon wickets as Brook, Jonny Tattersall, Matthew Fisher, Patterson, Coad and Duanne Olivier also fell.
When Coad departed, caught at third-man uppercutting at Douthwaite, Yorkshire were six runs short of the follow-on. But Bess successfully farmed the strike from Olivier, opening up the chance for the evening fightback to begin.
Coad had opener Nick Selman caught behind five balls into Glamorgan’s second innings before getting Lloyd caught at third slip and Kiran Carlson caught behind – 29-4 in the ninth over.
Sandwiched in between, Brook’s first of two catches at third slip was a sharp diving effort off Olivier to remove Ireland captain Andrew Balbirnie.