Chris Rogers blasted his second century of the LV= County Championship season as Middlesex dominated the bowling at Northamptonshire.
In-form Australia opener Rogers hit 106 and team-mate Dawid Malan made 92 as the visitors closed day two of their Division One clash on 262 for three.
Northampton hold a nominal 21-run lead, but Middlesex have given themselves the platform to chase victory.
Rogers' century added to his mammoth 241 not out in his county's brilliant victory over Yorkshire, and 82 against Warwickshire.
Malan blasted an unbeaten 85 in Saturday's Twenty20 defeat against Essex at Lord's and he too continued his good form.
Alfonso Thomas' five-wicket haul handed Somerset the initiative in their Division One clash against Durham at Taunton.
The 37-year-old South African claimed five for 41 as Somerset restricted Durham to 155 all out on day one at the County Ground, Scott Borthwick's 59 one of few highlights for the visitors.
Alex Gidman's 85 edged Gloucestershire towards their first Division Two victory of the season, after the hosts built a hefty 351-run lead over Kent at the County Ground in Bristol.
Hamish Marshall ended day two unbeaten on 66 as Gloucestershire reached 213 for four at stumps.
Captain Ramnaresh Sarwan fired 60 in his first Division Two innings of the campaign as Leicestershire levelled out proceedings with Hampshire at Grace Road.
Leicestershire closed day two on 296 for nine in their first innings, to trail Hampshire by 36 runs.
Angus Robson hit 54 and Rob Taylor 53, in response to Hampshire's 332 all out.
Hampshire seamer Kyle Abbott took four for 55, backing up 50 with the bat.
Monty Panesar's miserly four for 18, including six maidens, kept Essex in the Division Two fight at Worcestershire.
Saeed Ajmal's six for 75 looked to have put the hosts in control at New Road, only for Panesar to strike back.
Essex turned their overnight 52 for two into 203 all out as Ajmal took control.
Then Panesar's tight bowling restricted Worcestershire to 105 for eight at the close of day two.
Worcestershire lead by 193 but will not yet be fully confident of victory.