TIM Murtagh and Peter Trego impressed on the second day of the Specsavers County Championship Division One match at Lord's.

Middlesex seamer Murtagh returned his 27th first-class haul of five wickets or more and combative Somerset all-rounder Trego - also 34 - responded with his fourth half-century of the season.

The hosts then made good progress in replying to the visitors' score of 376, closing day two on 139 without loss.

Murtagh rocked Somerset by taking three wickets in three overs with the new ball after they resumed on 219 or two before Trego, two months his senior, revived them in a sixth wicket partnership of 113 with Lewis Gregory.

The pitch looked as placid as it had done on the first day when Somerset captain Chris Rogers scored a century against his former county, sharing an unbroken third wicket partnership of 125 with James Hildreth - so Murtagh deserves credit for his morning burst.

Rogers had added only five to his overnight 104 when he dabbled outside off stump and was caught behind.

Two balls later, Jim Allenby, pushing forward, edged to second slip and two overs after that Hildreth was leg before wicket for 68.

Murtagh also uprooted Trego's off stump with a wicked ball that came back and kept low - but not before the Somerset man had hit a typically belligerent 65 off 90 balls with nine fours and a six.

Ryan Davies became Murtagh's fifth victim when James Franklin caught him at the second attempt but he could not dislodge Gregory, who had made a disciplined 49 off 129 balls when he perished to the off-spin of Olly Rayner.

Murtagh finished with five wickets for 53 runs from 30 exemplary overs.

Sam Robson, the Australia-born opening batsman discarded by England two years ago, then continued in his rich vein of form in the hosts' reply.

The 26-year-old had scored 451 in his three previous innings at Lord's this season - 231 and 106 against Warwickshire, 114 not out against Nottinghamshire - and on Monday he added an unbeaten 67 off 130 balls with 10 fours.

Robson was dropped twice in the fifties - at point off Tim Groenewald and in the slips off Allenby - but with Nick Gubbins joining him in their impressive unbroken opening partnership with Nick Gubbins (65 not out) he had given Middlesex just the start they needed.