Moeen Ali's first double century allowed Worcestershire to declare at 505-7 on day two of their County Championship Division Two match against Glamorgan at New Road.
Glamorgan immediately lurched into trouble, losing two wickets in 20 overs before tea and three more in the final session before closing on 164-5, still 192 short of making the hosts bat again.
A shoal of statistics gathered around Moeen as he added 95 to his overnight score of 155 before Dean Cosker claimed his wicket for career-best 250.
The left-hander accumulated his runs from 367 balls with 26 fours and two sixes in a little over eight hours before a tired-looking shot found Mike Reed a few yards inside the boundary rope at long-off.
By then he had leapfrogged all of his rivals in the race to be first to 1,000 first-class runs this season. Now on 900, he is 11 ahead of Yorkshire and England's Joe Root.
A slow surface was made for a batsman intent on playing a long innings, although his performance was not entirely flawless with several shots skewing off the outside edge to the third man area.
Having posted Worcestershire's first double hundred in the championship for nearly four years, he went on to match Graeme Hick, Glenn Turner and Don Kenyon in becoming the fourth player to make 250 or more for the county on the New Road ground.
Nothing much went right for Glamorgan's bowlers when Worcestershire resumed with 322-3 on the board from the first day.
First they were held up for more than hour by Jack Shantry, the nightwatchman making 32 out of a stand of 70, and even when three wickets tumbled in a dozen balls, they were knocked by a stand of 101 between Moeen and Ben Cox.
Cosker emerged with most credit. After conceding 22 runs in his first two overs on Thursday, he straightened out his figures with a return of 4-68.