Tom Kohler-Cadmore completed his maiden LV = County Championship century before a rapid half century from Ben Cox helped Worcestershire achieve maximum batting points against Middlesex at New Road.
Kohler-Cadmore resumed on 97 not out and went to three figures with a cover drive for four off spinner Ollie Rayner from the fifth ball he faced today.
It was completed from 192 deliveries with 12 boundaries.
Kohler-Cadmore celebrated in the middle with his flat-mate Tom Fell and received a standing ovation from his team-mates on the dressing room balcony.
Fell, who yesterday completed 1,000 Championship runs in a season for the first time, added four to his overnight 167 before he was caught at cover off Neil Dexter.
He struck 25 fours and a six in his 267 ball innings and added 229 in 61 runs with Kohler-Cadmore.
Ross Whiteley (9) provided Dexter with another wicket, caught off a leading edge at third man, and the visitors rattled through 16 overs in the first 40 minutes to avoid a possible points deduction.
Cox ensured Worcestershire got to 400 and the five maximum batting points inside the 110 overs with a typically aggressive innings.
He hit Dexter for two sixes via a sweep and over long off and reached his half century off 37 balls.
Kohler-Cadmore was unbeaten on 130 from 235 balls with 13 fours and Cox 53 not out when the declaration came at 431-5 50 minutes before lunch.
The pair had added 78 in 12 overs.
Middlesex reached 39-0 from eight overs before lunch against the new ball attack of Joe Leach and Shannon Gabriel.