Western Storm 111 for 6 (Luff 60*) beat Northern Diamonds 110 for 9 (MacDonald 22, Harvey 2-20, Morris 2-24) by four wickets

Western Storm significantly boosted their chances of reaching Finals Day in the Charlotte Edwards Cup as they beat fellow challengers Northern Diamonds in a nervy low-scoring clash at Emirates Riverside.

Storm replaced the Diamonds at the top of Group B by recovering from 14 for 3 to chase 111 and win by four wickets with three balls remaining in this penultimate-round fixture, unbeaten captain Sophie Luff making an excellent 60 off 54 balls.

The win owed much to some expert bowling and fielding and sets up a fight for possibly two spots at Finals Day when Monday's last round takes place with three teams from Group Two still alive.

Storm are top on 13 points and Diamonds on 12 in second place. Thunder have 11 points in third. Only the top team in each of the two groups guarantees qualification for the September 5 showpiece, while the best second-placed finisher also advances to Southampton. Thunder play Diamonds at Chester and Storm face Sunrisers at Fenner's on Monday.

Having invited the Diamonds to bat, spinners Nicole Harvey and Fi Morris claimed two wickets apiece, while Georgia Hennessy returned a superb 1 for 15 from four overs of medium pace.

The skittish Diamonds suffered two run outs, including captain Hollie Armitage following a mix-up with Sterre Kalis coming back for two.

Lauren Parfitt also took a fine one-handed catch over her head at point after Linsey Smith miscued Hennessy to make it 56 for 5 in the 12th over.

The Diamonds, fielding two bowling debutants in Rachel Slater and Ella Telford, had got off to a bright start at 22 without loss after two overs before succumbing to the pressure applied by their visitors. Only Alex MacDonald, from number eight, reached 20 with 22.

But home hopes were raised with three wickets inside the opening four overs of the run-chase as Storm fell to 14 for 3. Smith's left-arm spin trapped Hennessy lbw with the first ball of the innings before 20-year-old left-arm seamer Slater bowled Morris and Gibson in her first eight balls.

Luff and Katie George then shared a calm and valuable 49 for the fourth wicket. Luff pulled Armitage's leg-spin for four and lofted her for a straight six, only to lose George, bowled for 14 in the same over as the score fell to 63 for 4 in the 12th.

Alex Griffiths and Natasha Wraith also fell before Luff, who reached her third Storm fifty of the summer off 44 balls, helped gain 18 off the last three overs and four off the last. Parfitt also added an unbeaten 20.