Ben Harmison celebrates taking the wicket of Stewart Walters on his way to 4 for 27 at Guildford © Getty Images

Leaders Kent endured a wretched day at Taunton where Somerset scored 427 and then reduced the visitors to 13 for 3 by the close. Five batsmen passed fifty, led by Zander de Bruyn's 81, as Kent's bowlers struggled to cope without Yasir Arafat who left the field with stomach cramps after four overs. James Tredwell came in for some severe punishment on an easy surface, shipping seven sixes on his way to 2 for 94. Somerset maintained a good pace all day, even when losing three quick wickets either side of lunch. Kent were left with a tricky five overs in gloomy and more bowler-friendly conditions and they lost Joe Denly, Martin Saggers and Robert Key. Key's wicket, held at the second attempt by wicketkeeper Craig Kieswetter, was the hammer blow off the last ball of the day.

Surrey's woes continued as they were bowled out for 220 by Durham at Guildford, and it was only thanks to 113 from Scott Newman that they avoided a complete collapse. The Harmison brothers took six of the wickets to fall, but the lion's share went to Ben who finished with 4 for 27, including three in 19 balls to polish off the innings. Surrey, missing several regulars through injury, including Mark Ramprakash who withdrew with a stomach upset, were fairly well placed on 199 for 4 when Liam Plunkett had Newman caught low down by Michael Di Venuto at second slip. Their last six wickets then fell for 21 runs on a pitch which contained few demons. Durham had problems of their own as Jimmy Ormond removed Di Venuto and Shivnarine Chanderpaul to leave them on 44 for 3.

Hundreds from Murray Goodwin and Carl Hopkinson helped Sussex to reach 316 for 5 against bottom side Hampshire at Arundel. The innings got off to a shocking start as they crumpled to 25 for 4 before the pair shared a fifth-wicket stand of 194. Even when Hopkinson departed after completing his maiden first-class century, Robin Martin-Jenkins (57*) helped Goodwin add another 97 by the close, both batsmen benefiting from dropped catches. Earlier, Chris Adams and Matt Prior both fell for 0 and Michael Yardy was cruelly run-out at the non-striker's end by a deflection from the bowler.

Jeff Evans raises his finger as David Balcombe celebrates running out Michael Yardy at Arundel © Getty Images
A fifth-wicket stand of 157 between Jim Troughton and Tony Frost bailed out Warwickshire against Middlesex in the top-of-the-table clash at Uxbridge. The pair came together with the leaders wobbling on 78 for 4 but were largely untroubled during their stand, although Ed Joyce at short leg did drop Troughton when he was on 32.

Five Derbyshire batsmen passed fifty as they closed on 352 for 6 against Northamptonshire at the County Ground. Aside from a ten-ball spell midway through the day when David Wigley took three wickets, the bat dominated. Paul Borrington, Greg Smith, Wavell Hinds and Jonathan Clare all made half-centuries, and Graham Wagg was unbeaten on 81 at the close.