In other games, Essex have left Maurice Chambers out of the squad in favour of Chris Wright, who makes only his second CC appearance this season. Can't help but think if Tsotsobe wasn't the overseas player, he'd have been the man to miss out.
Essex's opponents Derbyshire unsurprisingly have former Essex man Tony Palladino in the side, he'll share the new ball with Tim Groenewald, they have picked up over 30 wickets between them already this season, so a good test for England opener Alastair Cook. Derby have won the toss and will field.
Di Venuto and Phil Mustard are back in the Durham side against Somerset giving their batting a strong look. Onions rehab continues with another game under his belt, still no Harmison or Plunkett, so Callum Thorp and Ruel Braithwaite get another opportunity to cement a place. A specialist spinner included in Scott Borthwick.
No Craig Kieswetter after his century at the weekend, so Jos Buttler will keep. The exciting Lewis Gregory and Alex Barrow make their second career CC appearances. Gemaal Hussain and Steve Kirby will be buoyed getting a few wickets under their belt in their last run out in the CC.
Kent and Glamorgan is the final CC game starting today, Glamorgan look close to full strength, while Kent's injury problems in their bowling attack persist. Matt Coles, Dewald Nel and Neil Saker are the three specialist seamers, supported by all-rounders Darren Stevens and Alex Blake, and the experienced James Tredwell will be vital in the slow bowling role.