Lancashire's batsmen advanced to 239-7 on day three against Gloucestershire, well-placed to press for a third Championship victory on Saturday.
The hosts lead by 327 runs heading into the final day at Liverpool after Gareth Cross and Ashwell Prince both hit 64 and Wayne White scored an unbeaten 52.
Earlier Lancashire's bowlers had dismissed Gloucestershire for 222 to earn a first-innings lead of 88.
The morning's play was dominated by Gloucestershire batsman Alex Gidman, who converted his overnight 54 to 110 before he became Simon Kerrigan's fifth wicket when he pulled the slow left armer to deep square leg, where White leapt to take a fine catch.
Any hopes Lancashire had that building a substantial lead would be straightforward were rocked as early as the first ball of their innings when Andrea Agathangelou was caught behind off Craig Miles.
Two wickets apiece were bagged by the Gloucestershire seamers Liam Norwell and Graeme McCarter as the home side collapsed to 62-5, a lead of just 150, before Cross and Prince restored the home side's advantage with a 85-run stand for the sixth wicket.
Prince had hit eight boundaries in his 106-ball innings of 64, his fourth Championship score above 50, when he chipped Benny Howell's slower ball to Norwell at mid-off.
However, Cross and White flogged a tiring attack unmercifully to add 67 in 12 overs and ram home Lancashire's advantage.
Cross was eventually caught in the deep off Norwell, who ended the day with 3-80, but White completed his first fifty for Lancashire off 47 balls three overs before the close and ended the day with an unbeaten half century.