LV=County Championship Division Two, Sophia Gardens, Cardiff (day three):
Yorkshire 500: Shan Masood 192, Bean 93, Hill 71; Harris 3-131, Carlson 3-147
Glamorgan 273 (89.2 overs): Carlson 64; Revis 5-50, Coad 3-17 & 120-2: Byrom 52*, Northeast 45*
Glamorgan (2 pts) trail Yorkshire (7 pts) by 107 runs with eight second-innings wickets remaining
Matthew Revis and Ben Coad bowled Yorkshire within sight of victory as they forced Glamorgan to follow on in Cardiff.
The Welsh county resume on 120-2, still 107 runs behind, after being bowled out for 273 first time round.
Revis claimed a career-best five for 50 while Kiran Carlson top-scored with 64.
But Eddie Byrom (52 not out) and Sam Northeast provided sterner resistance second time around.
Resuming at 150-6, Glamorgan added 63 runs in 29 overs between the showers in an attritional first session, losing Carlson who fended a short ball to short leg as Revis claimed his fourth wicket.
Dan Douthwaite was briefly tempted to hook in the air by Revis as Yorkshire packed the leg-side field, but quickly thought better of it.
Douthwaite, in his first championship match since April, and Andy Gorvin settled into a pattern of gritty defence as spinner Dom Bess wheeled away unchanged with fielders clustered round the bat.
The new ball did the trick in style as Coad trapped Douthwaite lbw for 37 with his first delivery back, and produced a jaffa to hit James Harris' off-stump next ball.
Bizarrely, Coad (3-17) and Jordan Thompson were removed from the attack after two overs each with the new ball, and the visitors opted for some ill-advised tactics as the tenth wicket pair of Andy Gorvin (47) and Jamie McIlroy (30 not out) were able to settle in and then prosper for career-best scores.
Both hit their first sixes in the first team in a stand of 56 bringing an unexpected bonus point, before Revis cleaned up Gorvin's stumps to celebrate his maiden five-for.
With a day and a half to win the match, Yorkshire made early inroads second time round as Coad had Zain Ul Hassan caught at slip without scoring and Colin Ingram (14) edged Bess to slip.
Eddie Byrom and Sam Northeast did their best to dig in though Byrom was discomforted by some short bowling from a revved-up Revis, two successive balls just lobbing over wicketkeeper and slips.
Bess settled into another long spell and Yorkshire had to turn to double spin as the light faded, with Adam Lyth having Byrom dropped by both wicketkeeper and slip off the same ball as an edge brought his half-century up.
Northeast was the more settled of the two with some elegant drives taking him to 45 not out by the time the umpires again checked the light and ended Yorkshire's efforts for the day.
Glamorgan captain Kiran Carlson told BBC Sport Wales:
"The day was a bit up and down, a shame I got out early on because Dan and me could have built a nice partnership. But Andy Gorvin and Jamie McIlroy batted beautifully at the end (of the first innings), then Sam and Eddie put on a good partnership in tricky conditions.
"We've had to save games a few times this year, so we've got every confidence we can do that though we know Yorkshire are going to throw everything at us.
"All we can do is try and bat the day. The wicket is strange, sometimes it feels really flat but it's a bit two-paced and Matt Revis was tricky to face, so we're going to have to work out a way to challenge that."
Yorkshire bowler Ben Coad told BBC Radio Leeds:
"The pitch isn't offering too much, it's slow and low but the effort we've put in has been great and we've got our rewards. There's still a long way to go but the position we're in has been a brilliant effort so far.
"To bowl them out for 270-odd has given us the chance to win the game. When someone does rough batters up like (Revis), it's not that ball that necessarily gets the wicket but the one you follow up with.
"How far his bowling has come on in the last couple of years has been amazing, he's got some serious pace and on a pitch like that he's tough to play."