Kevin Pietersen put his England issues to one side with an imperious 163 for Surrey on the opening day of the LV= County Championship clash with Somerset at Taunton.
Batting for a minute short of four hours and facing 168 balls, Pietersen struck 20 fours and three sixes in Surrey's first innings total of 317.
Saj Mahmood claimed four for 62 but Somerset then lost openers Arul Suppiah and Marcus Trescothick with only 16 on the board before closing on 42 for two.
Ian Westwood led Warwickshire's drive for batting points and Paul Franks battled to keep Nottinghamshire in contention in the clash of Championship title contenders at Edgbaston.
Westwood made an impressive 81 and Franks took three for 52, but a stand of 102 by Tim Ambrose and Rikki Clarke protected Warwickshire's position at top of Division One as they closed on 298 for five.
Lancashire slipped still further into relegation trouble as they fell to 58 for five against Durham before the lower middle order battled back.
Graham Onions took three for 26 in 20 overs but Gareth Cross hit 57 in a stand of 72 with Tom Smith, who then added an unbroken 91 with Kyle Hogg on his way to 86 not out.
Skipper Daryl Mitchell made 129 not out to keep Worcestershire in the game on 295 for eight against Middlesex at New Road.
Mitchell's second Championship century of the season came off 273 balls and he put on 114 for the fourth wicket with Alexei Kervezee, who made 55 on his return to first-team action. Toby Roland-Jones took four for 67.