Spin duo Dom Bess and Dan Moriarty picked up four wickets each before pulsating knocks by Fin Bean and Joe Root set Yorkshire on course for victory at the halfway stage of their Vitality County Championship match against Glamorgan at Headingley.
Resuming on 109 for four, Glamorgan were bowled out for 221 in the early afternoon, with off-spinner Bess taking a superb four for 25 from 13 overs and left-armer Moriarty four for 74.
Division Two promotion favourites Yorkshire then batted positively and calmly on a used pitch that was showing more signs of turning, reaching 295 for two from 49 overs when bad light stopped play with 12 to bowl.
Unbeaten opener Bean hit a career-best 140 from 145 balls and Root 92 not out from 90. They put on 201 unbroken for the third wicket.
While current England star Root was closing in on a second successive Championship century, former England spinner Bess was making his first appearance of the season.
It was his best first-class score for Yorkshire since the opening match of 2023, when he took five for 158 in the second innings of a defeat to Leicestershire here.
Since then he has been dropped by Yorkshire, had two one-game loans to Warwickshire and Somerset and spent the winter playing domestic cricket in Zimbabwe, where he took five for 99 for Southern Rocks.
The Devonian, who is in the final year of his contract, began the summer in Yorkshire's second row behind Moriarty in the pecking order.
The 26-year-old's performances have earned him 14 Test caps, with the final coming in 2021.
Bess and Moriarty started the day with one and two wickets respectively in hand.
Moriarty made the morning breakthrough, having Chris Cooke well caught at cover by Harry Brook to end a 65-run stand with Colin Ingram as they reached 162 for five in the 56th over, the 15th of the day.
Ingram fell to Bess for 48 off only his second ball of the day to leave the innings on 182 for six.
After lunch, both men were caught at short leg.
Moriarty had James Harris caught off bat and pad before Bess had Tom Bevan caught off the back sweep for 22, again by Bean as the ball slipped off the glove in the next over - 208 for eight.
Bess was then at it again when he had Jamie McIlroy caught at backward square-leg for a wicket.
In the next over, Mir Hamza top-edged a slog sweep to Moriarty and was caught behind. The innings was over in 79 overs.
In total, six wickets fell in the afternoon, two of them in the early stages of the Yorkshire reply, despite them reaching tea on 106 for two from 20.
Adam Lyth was trapped lbw by Pakistan fast bowler Hamza before countryman Shan Masood was caught at short leg off Mason Crane's leg-spin for 34.
Yorkshire then upped the tempo in the evening, with Bean - dropped for six by Harris off his own bowling - and Root in partnership.
They took their toll on a Glamorgan attack that was missing several key players through injury.
On-loan pacer Crane was under particular pressure, taking 77 from just eight overs. Bean twice slog-swept him over long-on, either side of his 62-ball fifty, his second of the season. Root followed him to the milestone on 44.
Fifty-one runs had been scored in the first five overs of the evening and the third-wicket pair didn't let up in a display best described as men against boys.
The belligerent Bean reached his century off 111 balls and hit two more sixes, while Root was all touch and timing. He would have got there had the light not intervened.