Australian seamer Michael Hogan returned 5-43 as 13 wickets fell on the first day of Glamorgan's LV= County Championship Division Two clash with Leicestershire at Swansea.
Hogan passed 50 championship wickets for the summer while helping to bowl out the visitors for 203, but Glamorgan then stumbled to 36 for three in reply.
After winning the toss, Leicestershire made a useful enough start through openers Greg Smith and Niall O'Brien.
The first-wicket pair looked relatively untroubled as they reached 67 without loss in the 18th over before Glamorgan fought back to have the visitors 100 for three at the start of the 27th.
Smith was lbw to Hogan before O'Brien edged slow left-armer Dean Cosker to backward point six balls later.
After Leicestershire brought up three figures there was a notable moment for 20-year-old off-spinner Andrew Salter, who struck with his first ball in championship cricket to have Shiv Thakor caught behind by captain Mark Wallace.
Leicestershire duly slumped to 156 for seven after lunch as Hogan claimed three for four in 14 balls.
The beginning of Leicestershire's collapse saw Ned Eckersley go lbw shouldering arms to Hogan, who struck again two balls later as Tom Wells also departed lbw to a full-length delivery.
Hogan's productive spell from the Mumbles Road End also saw the end of Josh Cobb, who edged to Jim Allenby at first slip, and Glamorgan's dominance in the session was complete when Graham Wagg bowled Matthew Boyce.
Hogan completed his third five-wicket haul of the season nine balls after tea as Ollie Freckingham was trapped in front.
Salter's encouraging debut continued as he bowled Ben Raine for 37, although Leicestershire at least registered a solitary batting point before Cosker claimed the final wicket of James Sykes in the 81st over.
In reply Glamorgan lost both openers, Gareth Rees and Will Bragg, in the space of three overs. Rees was caught behind off Freckingham and Alex Wyatt had Bragg lbw.
There was further success for the visitors before the close, Freckingham having Ben Wright held at second slip.