Martin Guptill smashed a 101-ball century, including 19 fours and a six, as Derbyshire closed in on Gloucestershire’s first innings total of 275 on the second day of the LV= County Championship match at Bristol.
Dropped on 57 by Geraint Jones at slip off Liam Norwell, the 28-year-old New Zealander cut loose with some savagely struck boundaries to be unbeaten on 123 at tea with his side 270 for four.
Ben Slater, also dropped by Jones off the first ball of the day, contributed 56 and Billy Godleman 44.
Gloucestershire were let down by their fielding, with half a dozen chances being spurned as the pitch continued to offer something for the seamers.
Guptill made them pay, reaching his fourth first class century for Derbyshire with a glorious straight driven boundary off Craig Miles.