Nick Gubbins’ brilliant hundred earned Middlesex a first innings lead going into day four at Lords’.
Gubbins' ton came just minutes after Sam Robson was dismissed for 99, before Paul Stirling hammered 85.
Jack Leach took four wickets for Somerset with Jim Allenby prizing out three home batsmen as Middlesex will resume 402-9 on Wednesday, 26 runs ahead.
Hosts bring up 150 early on
After resuming 139-0 on Tuesday morning, Middlesex’s 150 came up within 20 minutes on day three as Gubbins saw two streaky edges go through third man for four, much to the displeasure of Jamie Overton.
Early morning probing from Overton, Allenby and Tim Groenewald came to nothing as Robson clipped one agonisingly wide of James Hildreth at midwicket.
Robson was dropped for a third time of the innings and second by Marcus Trescothick with the score 172-0, before the England international chopped a ball from Jack Leach onto his stumps one shy of his ton just after lunch with the score on 198.
With Robson contemplating what could have been, Gubbins showed him how it’s done by clipping Allenby through the leg side for three more to go through to his century from 208 balls.
Similar to the Somerset innings, after one wicket went, more followed.
Dawid Malan was first to go as he edged Allenby to Trescothick, who made no mistake at the third time of asking as Malan went for a brief five.
It was the same combination for the visitors shortly after as Gubbins tried to cut Allenby through point but his effort flew off the top edge to Trescothick, who took a smart catch at second slip to leave Middlesex 253-5.
Adam Voges displayed several cheeky paddle sweep shots to manoeuvre the spin of Leach, but Groenewald trapped the Australian in front for 18 when Middlesex’s captain was looking set for a big score.
Groenewald dismissed John Simpson in his next over as the variable bounce at Lords’ reared its’ head once again to leave the Middlesex wicketkeeper LBW for ten, which brought Stirling to the crease.
As Somerset’s revival started at five wickets down, so did Middlesex’s.
Stirling wasted no time in racing to 20 with two textbook cover drives and two trademark Paul Stirling pull shots, meanwhile James Franklin flashed at an Overton delivery that flew just wide of Tom Abell at point.
Franklin didn’t last too much longer as he edged Leach to Allenby at slip for 23 after a partnership of 49 with Irishman Stirling to end the mini-revival.
That brought Ollie Rayner to the crease, who took no time in attacking Leach with three powerful sweep shots that raced to the short leg side boundary at the home of cricket, whilst Stirling carried on where he started by smashing Leach over long on for six.
Tea brought Somerset some joy as Rayner went for one sweep shot too many and Leach had his third victim as Rayner fell LBW for 26 with the score at 372, a stand of 71.
With Stirling looking set for a hundred and to come back not out overnight, Leach claimed his fourth as the Irishman missed a full delivery and was given out LBW by umpire Nigel Bainton with just four overs left in the day.
That left the tail at the hands of the Somerset bowlers who claimed one more wicket before the close, Allenby picking up his third after Toby Roland-Jones’ leading edge went straight up to Chris Rogers at mid-off.
With this one heading for a draw, Middlesex will resume 402-9 on Wednesday.