Surrey 626 for 6 (Burns 199, Solanki 143, Roy 121*, Ansari 98) lead Gloucestershire 112 by 514 runs
Rory Burns fell just one run short of a double-century as Surrey smashed a host of records in heaping a mammoth total of 626 for 6 on ramshackle Gloucestershire in Bristol.
Burns was not alone in falling short of a personal milestone, with Zafar Ansari slipping two short of his maiden first-class century. Burns' 199, Ansari's 98 and Jason Roy's red-hot unbeaten 121 from just 71 balls - only his second first-class hundred - were all new first-class personal bests.
Vikram Solanki also fired 143 as Surrey refused to be contained in the West Country. Gloucestershire's 112 all out is a mere speck on the County Ground horizon after two days, given Surrey's 514-run lead.
Surrey had resumed on 186 without loss, with Ansari 84 and Burns 98 overnight. Spin-bowling allrounder Ansari followed up his 77 not out and 62 against Worcestershire at The Oval at the start of the month with another fine knock, surpassing his previous best of 83 not out.
Burns eclipsed his previous top score of 121 as the visitors applied a constant chokehold - and then Roy hammered past his 106 not out highest knock without consummate ease.
Ansari proved the day's first dismissal, just two runs shy of that maiden first-class century, Alex Gidman holding the catch from Benny Howell's bowling. South Africa's new Test captain Hashim Amla was unable to force a start, trapped leg before by Will Gidman for just 9.
Surrey breezed away from leaking two wickets for 12 runs, Burns ticking along at a solid rate and new partner Solanki raising the pace. The vastly-experienced 38-year-old blasted his century from just 112 balls as the visitors showed their superiority.
Burns and Solanki put on 212 for the third wicket as Surrey seriously ratcheted up proceedings, Burns homing in on a double century. Just as he was lining up his celebrations though, Liam Norwell had him caught by Alex Gidman, just the one agonising run short.
Unsatisfied with 439 for 3, greedy Surrey kept on dismantling the Gloucestershire attack. Steven Davies fell to Will Gidman for 9, but Solanki moved on to 143 before he was removed, by Matt Taylor.
Sensing a slog-fest, Roy stepped into the fray and produced the innings of the day, where aggression was concerned at least. His howitzer hundred came from just 55 balls and 67 minutes, including nine fours and seven sixes. Gary Wilson then hit 26 before he was clean bowled by Norwell, with Gareth Batty 4 not out at the close.