Derbyshire 377 (Andersson 105, Chahal 6-118) and 52 for 4 trail Northamptonshire 550 for 9 dec (Broad 171, Keogh 125*) by 121 runs
Allrounder Justin Broad hit a brilliant 171, his second score in excess of 150 this month amid a Northamptonshire run-fest against Derbyshire at Wantage Road as the hosts racked up a mammoth 550 for nine declared.
Returning from a wrist injury, Broad struck 18 fours and a six, following his maiden first-class ton, 157 not out at Canterbury at the beginning of July. On a day of records, his 171 was the highest score ever made by a number seven from any team against Derbyshire.
With Rob Keogh also striking an excellent unbeaten 125, the pair put on 208, the highest seventh-wicket partnership for Northamptonshire against Derbyshire as the visitors' attack wilted in the afternoon sunshine.
Luis Reece was the pick of Derbyshire's bowlers, finishing with figures of three for 114.
Northamptonshire declared 173 ahead and reduced Derbyshire to 52 for four at stumps, Indian legspinner Yuzvendra Chahal picking up two wickets in two balls. It leaves the visitors with a mountain to climb on a pitch offering turn and bounce, still trailing by 121 at the end of day three of this Rothesay County Championship fixture.
Earlier, resuming on 265 for five, Broad and George Bartlett extended their sixth-wicket partnership to 127, also the highest for Northamptonshire against Derbyshire. But after posting 66, his highest score this season, Bartlett was trapped lbw by a Ben Aitchison delivery which nipped back and kept low.
Broad and Keogh though looked relatively untroubled by a lacklustre Derbyshire bowling display throughout the morning as they focused on building a partnership and taking a first innings lead, picking up a handful of boundaries along the way. Broad, 64 overnight, deployed the pull against Zak Chappell and on drove handsomely, while Keogh swept and reverse swept against Joe Hawkins' spin.
Broad lunched nervously on 99, but despite flashing outside off stump against Martin Andersson after the break, he took a single off Hawkins to celebrate his first century at home.
With the scoring rate accelerating, Keogh drove Andersson sweetly through midwicket to reach his second successive half-century off 112 balls and crunched Andersson through extra cover to bring up the 100 partnership and put Northamptonshire ahead. Broad then punched Blair Tickner down the ground for another boundary.
Derbyshire plugged away, trying several short-term experiments to try to force a breakthrough. Andersson bowled consistently wide outside off-stump to Broad, while Aitchison reverted to bowling spin. Then for Chappell, three fielders were stationed in the area between mid-on and short midwicket.
But Northamptonshire's batters continued unabated, Keogh cutting Tickner to backward point to bring up the 150-partnership before passing the previous highest seventh-wicket stand (163) by Josh Cobb and David Willey at Derby in 2015.
Frequent Northamptonshire milestones continued to keep the public address announcer busy, Keogh turning Andersson away for two to bring up his century, Broad taking a single next ball off Hawkins to reach his 150.
In a scrappy passage of play before tea, Derbyshire's tired fielders shelled three catches, but picked up one vital wicket in between. First, Keogh, on 101, swept Hawkins firmly to short midwicket where Madsen put down a straightforward chance. Then after Broad smashed Reece through extra cover, Caleb Jewell dropped one at backward point off an attempted reverse sweep.
Undeterred, Broad and Keogh celebrated their 200 partnership, Broad swinging Reece for six into the sightscreen as Northamptonshire accelerated further. Broad's 273-ball knock finally ended though when he hit Reece down the ground again but was caught just inside the ropes.
George Scrimshaw won an immediate reprieve when Aitchinson failed to hold a one-handed grab at first slip off Reece. But his intentions were evident as he quickly went on the offensive against Hawkins.
Tickner struck after tea castling Scrimshaw with a full and straight delivery, but Keogh found good support from Liam Guthrie (22), Northamptonshire declaring when Hawkins had the Australian caught hitting down the ground.
Derbyshire's reply started ominously when Jewell flashed outside off, Ricardo Vasconcelos snatching the ball at first slip.
Promoted to opener Zak Chappell made 22 before Chahal's double strike. First Chappell reverse swept straight to backward point, then Harry Came was lbw playing back to a slider. Finally skipper Wayne Madsen edged Keogh to Broad at first slip to further compound Derbyshire's woes.
