Luke Procter hit his maiden first-class century as Lancashire fought back strongly on the second day of the LV= County Championship match with Gloucestershire at Bristol.
The Division Two champions-elect moved from an overnight 33 for two in their first innings to 292 for seven, Procter hitting 106 and Tom Smith 88 not out; Will Gidman was the pick of the home attack with 4-58.
Lancashire were 38 for three and 105 for four prior to a partnership of 159 between Procter and Smith that turned the course of the match.
It enabled the visitors to move two bonus points nearer the title, having already clinched promotion and ensured a memorable day for Lancastrian Procter in particular. His previous best first-class score was 89 against Sussex in 2011.
The 25-year-old Oldham-born left-hander heralded his ton off 208 balls, with 13 fours. On reaching it, he removed his helmet and raised both arms to the skies before being congratulated by partner Smith.
Procter had arrived at the wicket with the total on 38 when Gloucestershire wicketkeeper Gareth Roderick produced a superb diving catch to his right to send back Karl Brown for 23 off Gidman.
Luis Reece helped add 67 as he sought an eighth successive half-century and a share of a county record. But the 23-year-old opener fell 15 short when bowled by left-armer David Payne attempting a big shot in the 32nd over.
It was 115 for four at lunch and the afternoon session saw Smith survive a difficult chance to Michael Klinger at midwicket off Benny Howell when on 16. It was the second catch put down by Gloucestershire as Alex Gidman had spilled Reece, on 34, at first slip to deprive young Matt Taylor of a maiden first-class wicket.
Procter reached his fifty with a glorious straight drive off Benny Howell and Smith followed to a half-century off 128 balls, with eight fours.
The pair batted right through the afternoon and by tea had taken the score to 206 for four. With 21 runs added, Gloucestershire took the second new ball.
It finally broke the partnership with the total on 264 as Will Gidman, frustrated at having several big appeals rejected, finally pinned Procter lbw playing across the line.
Smith made good use of the reverse sweep against his namesake, Gloucestershire left-arm spinner Tom Smith, and also stood tall to dispatch the quicker bowlers with some attractive back-foot shots.
Left-arm seamer Taylor, 19, did get his maiden championship wicket when Alex Davies was caught behind driving for 12. And Howell followed up by having Glen Chapple caught at mid-on for a single.