Sussex's relegation worries grew as they went down to a 20-run defeat to Middlesex at Lord's.

A wearing fourth-day pitch was expected to assist the spinners, but James Harris took four wickets and Toby Roland-Jones three as Sussex fell just short after being set 266 to win in 85 overs.

Ben Brown (68) and Chris Nash (66) both made half-centuries but Middlesex found the happy knack of taking a wicket just when the momentum looked like it might be swinging Sussex’s way while skipper James Franklin saw wickets fall three times in the over after he made a bowling change.

With Hampshire winning, Sussex are now just three points off the bottom of Division One and relegation to the second tier for only the second time since 2001 looks a real prospect, especially as two of their last four matches are against champions-elect Yorkshire. Middlesex, meanwhile, will feel they are in pole position to finish second after moving above Warwickshire with their fifth win of the season.

Harris produced the telling spell of the day before lunch when he knocked over Sussex’s top three in his first two overs after joining the attack in the 11th over.

With his first ball he had Luke Wells (16) caught behind off an attempted cut. Ed Joyce (22) was lbw to a ball that swung late and Matt Machan (5) held at slip.

Sussex never really recovered from that although Nash did his best to keep them in with a chance despite losing Mike Yardy and Luke Wright after lunch. Yardy (11), bowled by Ravi Patel, was the only batsman to fall to spin while Wright (20) was well held on the stretch by Ollie Rayner at second slip after hitting four boundaries in a brief counter-attack to give Tim Murtagh his 500th first-class wicket for Middlesex.

Nash reached his 50 just before a shower drove the players off and on the resumption he had added 12 more when he tried to upper-cut Roland-Jones over the slips and Rayner took another excellent catch. Nash faced 85 balls for his 62 and struck 11 fours, putting on 60 for the sixth wicket with Brown.

Brown and Ashar Zaidi took the target down to 69 and Zaidi swept Rayner for a flat six to mid-wicket before Roland Jones had him caught behind for 16.

Ollie Robinson (10) gave Roland-Jones his third wicket when he was caught at second slip and Harris came back into the attack to have Steve Magoffin (1) brilliantly caught by Dawid Malan low down as he dived forward on the mid-wicket boundary.

With 51 still needed the game looked over, but last man Chris Liddle helped Brown add a further 30 runs. Brown rotated the strike excellently, Liddle defended doggedly when called upon and Middlesex were forced on the defensive.

But Franklin made another decisive bowling change, bringing back Murtagh after Roland-Jones had bowled a marathon 15 overs spell from the pavilion end. With his fourth ball he had Brown held by Franklin on the square-leg boundary for 68 (11 fours), the crestfallen Brown hurling his bat to the ground in disgust after a tame end to what was nearly a match-winning innings.