Middlesex enjoyed a superb second day at Lord’s as they took complete control against LV= County Championship leaders Sussex.
Aided by Neil Dexter reaching three figures and 50 from wicketkeeper John Simpson, Angus Fraser’s side pressed on to 499 for eight declared in their first innings.
Sussex were then reduced to 147 for seven as their former spinner Ollie Rayner picked up 3-47.
The follow-on now beckons and Middlesex, who began this game just 10 points behind Sussex in third place, are sniffing blood against the only other unbeaten team in the top-flight.
Sussex’s reply got off to a miserable start as Tim Murtagh had Chris Nash held at third slip in the fifth over.
Nash made 13 and the rest of the visiting top five followed suit by reaching double figures, only to then be dismissed.
Luke Wells skied an attempted pull at Toby Roland-Jones just before tea when he had 19.
Rayner than claimed his first scalp, having Ed Joyce stumped for 20 when the Sussex skipper overbalanced looking to drive.
A fine spell from James Harris brought the wickets of Michael Yardy and Chris Jordan, who were lbw for 22 and nought respectively.
In between those departures, Rayner removed Matt Prior with the aid of a disputed low catch by Sam Robson at silly point and accepted a return chance offered up by Ben Brown.
Thankfully for Sussex, Luke Wright demonstrated defiance en route to 38 and the all-rounder received stoic support from Will Beer, whose unbeaten six spanned 51 balls.
The day began with Middlesex on 320 for three, and Chris Rogers took his overnight 161 to 184 before attempting to hit Steve Magoffin over the top and being well-held by Yardy back-pedalling from mid-off.
Rogers faced 305 balls and hit 22 fours, his fourth-wicket stand with Neil Dexter bringing 155 runs to ensure a significant Middlesex total.
Dexter completed an excellent hundred of his own before edging Beer to slip on 104.
Simpson's half-century kept Sussex on the back foot, while Gareth Berg, with 39 from 25 balls, provided handy acceleration prior to the mid-afternoon declaration.