Martin Guptill recorded his highest ever first-class score as Derbyshire took complete control on Day Two at Bristol, finishing on 511-8.
The New Zealand international scored an incredible 227 runs, his maiden first-class double hundred beating his previous best of 195 not out, as Derbyshire dominated with the bat on a breath-taking second day.
Guptill scored over 100 runs in each of the last two sessions, hitting 29 fours and 11 sixes in a sensational 176-ball stay at the crease.
There were also valuable contributions from Shiv Thakor (83) and Ben Slater (56) as Derbyshire ended the day with a lead of 236 runs, in a day where they scored an astonishing 487 runs.
Guptill said: “It was the sort of pitch where I thought if I tried to bat time I would get a nick so I decided to go for it. When you take that approach you need a bit of luck and I had some today.
“When the second new ball was taken I started trying to hit everything out of the park. It was harder, so it came off the bat better.
“It’s taken me quite a few games to hit a first class double hundred. I got stranded on 195 a few years ago for Auckland and it’s nice to have reached the landmark.”
Derbyshire started well early on, as openers Slater and Godleman survived a few close shaves to guide the visitors through the first hour unscathed.
Gloucestershire got the breakthrough in the 27th over, as Godleman was caught behind for 44 off the bowling of Liam Norwell.
Guptill came to the crease with the score at 88-1 and he acquitted himself well alongside Slater who brought up his half-century shortly before the interval as the teams took lunch with the score at 118-1.
The pair continued to impress after the break until Slater was caught at slip for a well-made 56 with the score at 162-2. Matt Taylor then took two wickets in two overs to dismiss first Madsen, and then Durston as Gloucestershire threatened to gain the upper hand.
But Guptill was in dominant mood and continued to find the boundary regularly in the afternoon to bring up a superb century from 101 balls. Alongside Shiv Thakor, he helped guide Derbyshire to 270-4 at tea, just five runs behind Gloucestershire’s first innings total.
The duo were in imperious form after tea as they piled the pressure on Gloucestershire’s bowling attack, scoring 90 runs in the first 10 overs after the restart.
Thakor reached 50 for the first time in a Derbyshire shirt, while Guptill moved past 150 as Derbyshire looked to press home what was becoming a big advantage.
A fifth-wicket stand of 190 came to an end with the score on 380, as Thakor (83) was caught behind off Taylor, 17 runs shy of his century.
Despite losing the wicket of Alex Hughes the following ball, Guptill continued to swing the bat as the crowd at Bristol were treated to a special innings.
Three successive sixes from Guptill brought up his double-century off just 165 balls and in the process saw him record his highest ever score in first-class cricket.
Guptill eventually fell for 227 as he smashed a full toss straight down the throat of Peter Handscomb, bringing an end to a superb batting display.
A late cameo from Harvey Hosein, including hitting successive sixes off Handscomb, guided Derbyshire through to the close on 511-8.
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