Kyle Coetzer and David Sales both struck centuries as Northamptonshire's batsmen dominated the second day of their LV= County Championship Division Two clash against Gloucestershire at Wantage Road.
Scotland international Coetzer was the first to reach his milestone as he made 122 off 230 balls to help promotion-chasing Northants to eventually close on an imposing 369-3 - a first innings lead of 11.
Sales was to put some previous patchy form behind him as he then hammered an unbeaten 126 from only 137 deliveries, while captain Stephen Peters also contributed 87 off 153 balls.
Northants began the day on 13 without loss, 345 runs behind their opponents, with Peters resuming on 12 and Coetzer on one and the pair had progressed the score to 112-0 at lunch as Gloucestershire's attack struggled to get much out of a placid wicket.
In the end it came down to 18-year-old first-class debutant Tom Shrewsbury to finally break the stand on 170 when he forced Peters to edge to Gloucestershire wicketkeeper Gareth Roderick.
But any hopes the visitors had of this breakthrough bringing a change of fortunes were dashed as Sales piled on 135 alongside Coetzer for Northants' second wicket.
Having batted so well, Coetzer finally departed tamely in the final over before the second new ball was due when he chipped Benny Howell to Chris Dent at midwicket.
But there was no stopping Sales completing an explosive century - his 27th first-class ton - off just 107 deliveries with a crunching four through midwicket off James Fuller.
Alex Wakely (13) then became the first batsman to miss out on a big score as he nudged Fuller behind with five overs of the day left.
Australia international Cameron White then survived until the close along with Sales and will resume tomorrow on six not out with the hosts looking for a huge total.