Somerset 172 (de Lange 51, Murtagh 4-46) and 285 for 6 (Abell 84, Bartlett 76*, Gregory 64*) beat Middlesex 313 (Robson 165, Gregory 5-68) and 143 (Eskinazi 53, Davey 3-16) by four wickets

A nerveless, unbroken stand of 98 in 19 overs between George Bartlett and Lewis Gregory took Somerset to an improbable win at Lord's, as they chased down their target of 285 with four wickets to spare.

Victory had appeared unthinkable, both when they fell to 89 for 9 in their first innings and when Middlesex had compiled a lead of 254 with seven second-innings wickets in hand, but two spirited fightbacks - with Jack Leach at the centre on both occasions - set up an attainable target under cloud cover and floodlights on the third afternoon. Tom Abell's fluent half-century laid the foundation before bad light and drizzle brought an early close, and once he had found his rhythm again under blue skies on the final morning, Somerset became favourites for the first time in the match.

Then, a twist. Ethan Bamber took two wickets in 13 balls - Abell edging behind, Steven Davies trapped lbw by an in-ducker - to peg the chase back, and when Tim Murtagh induced the thinnest of edges from Craig Overton on the stroke of lunch as the clouds began to roll in, it seemed that the chase would prove too steep even for Somerset's long batting line-up.

But Gregory, fresh from a first-innings five-for, strode out after the interval and realised after poking defensively at his second ball, which jagged past his outside edge, that there was nothing to be gained from hanging in while Murtagh was nibbling it around. Instead, he used his considerable limited-overs experience to thrash 62 not out off 72 balls, dominating the seventh-wicket stand alongside the more reserved Bartlett. Gregory crashed Bamber through the covers to level the scores just as the drizzle returned, then clipped him behind square on the leg side to draw a guttural roar from the Somerset balcony.

Bartlett has prevailed in tough situations before in his Somerset career, most memorably in another successful chase at Edgbaston two summers ago, but this innings - which spanned nearly four hours - was one of his best. It was not always pretty - plenty of his runs came through third man - but his support role in partnership with Gregory was vital. He was particularly strong cutting and pulling against the change bowlers, and vindicated the decision to pick him ahead of Eddie Byrom.

Defeat would have left Somerset stuck in the red, following the rollover of their eight-point pitch penalty into the 2021 season, but instead they will head into their local derby against Gloucestershire on Thursday feeling bullish. "We tried not to read too much into it [the points deduction]," Abell said afterwards, "but this has done our confidence the world of good.

"We speak about it quite often: it's one thing being good as front-runners, but it's another thing when your backs are against the wall, coming from behind in games and still getting results. The mindset was really positive, with the way we'd got ourselves back into the game. We let ourselves down in the first innings - I don't think that was a true reflection of the wicket or how good we are as players - and we wanted to put that right."

Abell's own innings in the cold had set things up overnight, in a 79-run stand with Tom Banton for the second wicket, and with Gregory finishing things off with his counterpunch after lunch, all three of Somerset's Covid contingent made significant contributions despite their abbreviated pre-season following three weeks in solitary confinement. "When we were in the field yesterday and it was freezing cold, I said to Lewis, 'It could be worse - at least we're not in hotel isolation in Karachi'," Abell said. "We're so happy to be back playing for Somerset - it's very special to be back with the group, and to get the first win is even sweeter."

For Middlesex, this was a chastening loss. Stuart Law had dished out some hard truths in the dressing room on Saturday night, but all five of their bowlers conceded more than three runs an over across the third innings and struggled to keep a lid on the scoring rate. Leach's success in the holding role served to highlight the lack of a spinner in the Middlesex attack - though Thilan Wallawawita might well have played if he had been fit - and Stevie Eskinazi, the stand-in captain, was not proactive enough on the final day, particular when Gregory was seizing the initiative after lunch. He will be relieved to hear that Peter Handscomb should be out of quarantine in time to lead the side in the Surrey fixture on April 22.

Since Law took over at the start of the 2019 season, Middlesex's five first-class wins have all been relatively comfortable - four by 78 runs or more, and one by five wickets. Their title win in 2016 featured close wins at Taunton and in the decider against Yorkshire at Lord's, and they prevailed in a number of tight games in the two difficult seasons that followed, but on this week's evidence, that killer instinct seems to have deserted them.