Glamorgan built a lead of 223 over Gloucestershire on the second day of their LV= County Championship opener.
Kiran Carlson (108) and Billy Root (104*) both hit centuries while Eddie Byrom made 81 as Glamorgan dominated day two at Sophia Gardens.
After losing the early wickets of nightwatchman Timm van der Gugten, David Lloyd (9) and Sam Northeast (9), Carlson and Byrom put on a magnificent 160 stand for the fourth wicket as Glamorgan swung momentum back in their favour.
Glamorgan ended the day on 388/8, just twelve runs short of a fourth batting bonus point, and 223 in front of Gloucestershire.
"I think we're in a great position going into day three," said Carlson.
"Obviously it was tough early on, I think it's still doing a bit with the new ball.
"It was nice to spend some time out there, Eddie and I put on that big partnership which was great and thankfully we're in a great position going into day three."