McCullum strengthens dominant Bears

Last year's finalists meet as the season turns into its second half with both teams in the quarter-final positions. Lancashire's hard-fought win against Durham on Thursday was a huge result for them - had they lost they would have been sixth; as it is they are fourth. Birmingham, meanwhile are two points clear of Lancashire in joint first and, having won eleven of their last thirteen and four of their last five away, are the most consistent team in the country.

Brendon McCullum will make his Birmingham debut ahead of playing all seven of their remaining fixtures. Birmingham have also added Varun Chopra to the squad that beat Yorkshire last week while Keith Barker has been left out. Lancashire have named an unchanged squad

Yorkshire registered a crucial win against Nottinghamshire last Friday to give hope to their season but their defeat against Birmingham on Sunday punctured any sense of momentum. For the second week running Yorkshire head into the weekend for what will be a must-win encounter and Director of Cricket Martyn Moxon believes inconsistency of selection has hamstrung Yorkshire. "We have got to try to get a settled team and get some consistency into our play, which we haven't had yet. We have got to do it pretty quickly because we can't afford too many more losses."

Yorkshire will meet a Leicestershire team who have pleasantly surprised many on-lookers with consistently strong form and who currently sit third in the group, one point off first. Leicestershire will be without Umar Akmal who has left for the Caribbean Premier League but can call on the services of Grant Elliot once again. Leicestershire have added Kevin O'Brien, Ollie Freckingham and Rob Sayer to the squad. Akmal, Charlie Shreck and James Sykes are out.

Yorkshire have recalled Adil Rashid and have added Ben Coad, who has never played a professional T20. Tim Bresnan and James Middlebrook are rested, as is Gary Ballance, the out-of-form Alex Lees and Jack Brooks.

With Derbyshire in ninth and Nottinghamshire in eighth this East Midlands derby is a must-win match for both teams, and even then qualification for the quarter-finals may already be beyond them. Nottinghamshire have won just three times and have not strung consecutive wins together this season and the same can be said of Derbyshire who have won just twice.

Shared territory at the bottom of the group is as far as the similarities run between two markedly different teams. Nottinghamshire boast one of the most star-studded, powerful squads in the country, while Derbyshire are more inconspicuous, differences not evident on the pitch.

The statistics favour Nottinghamshire, with the county having won their last eight away matches against Derbyshire and their last 14 out of 16 overall. Nottinghamshire, who play again on Saturday against Northamptonshire, have named Alex Hales in their squad now that he has returned from international duty. Derbyshire have made one change to their squad that was beaten at Worcestershire last week, preferring Will Davis to Greg Cork.

This match brings together the two form sides of the North Group, with top of the table Worcestershire having won five of their last six matches and Northamptonshire having won three of their last four.

Despite Northamptonshire's strong recent form, their poor start to the season in which they lost three from three ensures this double-header weekend, in which they play Worcestershire and then Nottinghamshire, takes on huge importance. Such is the condensed nature of the North Group, two wins could elevate them towards the top of the table, while two losses could have the opposite effect. Northamptonshire welcome back David Willey to their 12-man squad while Worcestershire have added Alexei Kervezee.

Essex v Hampshire, with the two teams in second and third, is the top of the table clash and with Kent not playing this weekend, the winners will go first. Hampshire's defeat against Sussex last week robbed them of their third consecutive victory but they have won four of their last six, while Essex have won four of their last five. But only have four matches remaining.

Hampshire have made one change to their squad that lost to Sussex last week with Sean Ervine injured; Joe Gatting replacing him. Gatting is only the 16th player Hampshire have named in their squads this season. Essex hope that David Masters recovers from a groin strain.

Surrey began the season, as ever, with high profile overseas signings and optimistic of their chances, but they lie bottom with just two wins - only Derbyshire have won so few. Glamorgan's thrashing at the hands of Sussex last week saw them slide them down to sixth, but a win would bring them level with the loser of Essex v Hampshire.

Glamorgan have included Wayne Parnell in their 12-man squad for what will be Parnell's final math. Glamorgan have named only 14 players in nine squads this season - fewer than any other county which is in direct contrast to Surrey who have selected 23 players across eight squads - no county has named more. Surrey recall Jason Roy after his time away with England and select stop-gap overseas signing Dean Elgar in their squad. Tom Curran and Dominic Sibley are left out.

This is a low-table clash between Middlesex in eighth and Somerset in seventh. Only a couple of weeks ago Middlesex had won twice in a row having twice scored more than 200, since then however they have lost four matches in a row and are in desperate need of a win to keep their season alive. Somerset were in a similar position last week having lost three of their last four before they beat Gloucestershire in a tense west country derby.

Middlesex, who have lost nine of their last 11 completed home matches, have made two changes from the squad that was beaten by Hampshire two weeks ago, bringing in Eoin Morgan and Ravi Patel and leaving out Toby Roland-Jones and Neil Dexter. For Somerset, Abdur Rehman reyturns to the squad now Sohail Tanvir's stint as Somerset's overseas player has come to an end. Marcus Trescothick is left out for the second week running.

While Sussex won their local derby against Hampshire last week, Gloucestershire slid to defeat against Somerset, but despite the contrasting fortunes they are closely placed in the table with Sussex in fourth and Gloucestershire in fifth.

Sussex have named an unchanged squad from last week's ten-wicket demolition of Glamorgan, although Mike Yardy and Ashar Zaidi will undergo late fitness tests. Gloucestershire are hoping to welcome back Hamish Marshall, who missed the last three matches with injury, back to their team and he has been named in their 13-man squad. Robbie Montgomery who was named last week against Somerset misses out.