By the close the visitors' lead of 104 had been extended by a further 43 runs without loss.
Another Caribbean Test maestro, Desmond Haynes, continued his extraordinary run at Uxbridge, with yet another century for Middlesex, against Northamptonshire.
Haynes, who has now hit four centuries in eight innings at Uxbridge (average 134.6), struck a six and 17 fours in an unbeaten 127 as Middlesex declared on 220 for 5 - 149 behind Northamptonshire.
At Southport, Lancashire are poised to claim their first Championship win in 10 games. Although they slumped to 280 all out, a lead of just 23 over Leicestershire, their spinners, Dexter Fitton and Alex Barnett, reduced the visitors to 141 for 7 in their second innings at the close.
On a rain-affected day at Sheffield, Craig White hit 54 not out - his fifth successive half-century - as Yorkshire declared on 301 for 6. In reply Warwickshire are 88 for 0.