Leaders Nottinghamshire crashed to a heavy defeat against Durham at Chester-le-Street but still hold a commanding lead with two games remaining in the County Championship First Division.
Nottinghamshire took six points from the match to lead Somerset by 22, with Yorkshire, who go to Trent Bridge next week, a further three adrift.
After being set a victory target of 391 in 78 overs, on a pitch on which Durham added 82 in just over an hour in the morning, the visitors' attempts to bat out the day were undermined by Ben Harmison's blitz of three wickets in four balls.
With Mark Davies taking no further part after developing a sciatic nerve problem on the second day, Durham also lost Liam Plunkett, who limped off after bowling two overs with the new ball.
Harmison was on for the fifth over of the innings and conceded 24 in four overs before lunch. There was a wide in his first over after the break but, with the score on 51 for 1, he suddenly got it right in his seventh over.
Alex Hales pushed forward and edged to Michael Di Venuto at second slip and the next ball, perfectly pitched on off stump, bounced steeply. Australian Adam Voges, also pushing forward, edged it to wicketkeeper Phil Mustard. The hat-trick ball was short and wide, allowing Samit Patel to collect two easy runs, but the next delivery pinned him lbw on the back foot.
A stand of 30 between Mark Wagh and Ali Brown was broken by Ian Blackwell, who had both lbw and later had Luke Fletcher caught at silly mid-off to finish with 3 for 23 in 19 overs.
Harmison had 4 for 70, his final victim being Chris Read, who drove wide of off stump and edged low to third slip, where substitute Gareth Breese held a good catch.
Andre Adams, slogging at almost every ball, skied a catch to mid-on off Mitch Claydon, and the only resistance came from Steven Mullaney. He was last out for 64, skying an attempted pull off Scott Borthwick for Mustard to take the catch 10 minutes before the start of the final hour.
Durham's fifth win of the season ended any relegation worries, but their hopes of a title hat-trick remain slim. Nottinghamshire need only five points from two games to deny them.
In the morning, Blackwell had failed to add to his 50, edging Fletcher to Read, but Borthwick played beautifully for the second time in the match, scoring 43 in an unbroken stand of 79 with Mustard, who was on 51 when he declared with the score on 361 for six.Reuse content