Alan Richardson moved his match figures to 11-71 as Worcestershire closed in on victory in their LV= County Championship Division Two with Gloucestershire at New Road.
Worcestershire were dismissed for 457 in their first innings before Richardson helped reduce Gloucestershire to 87-5, leaving the hosts needing 136 more to avoid an innings defeat at the end of day three.
At the age of 38, Richardson is in the form of his life with career-best match figures of 12-63 in a recent two-day win against Kent and another 10-wicket return this time out.
The home side resumed on 302-3, with centurion Moeen Ali (123) an early casualty before Gareth Andrew smacked 66 from 71 balls and put on 98 with Jack Shantry (31) before Craig Miles mopped up the tail to finish with figures of 6-99.
Gloucestershire were soon wobbling as Richardson brought one back into the pads of Chris Dent (12) and claimed a second success in his next over when he had Dan Housego caught behind for a duck.
Hamish Marshall stayed for more than an hour but could only add 12 to the total, while Alex Gidman also fell to Richardson (3-34) for 32 after also sending one behind to wicket-keeper Michael Johnson.
Rain delays during the afternoon gave some respite but it will take an unlikely turn of events for them to save the match on Saturday.