Stephen Peters' unbeaten 61 secured Northamptonshire a Twenty20 Cup home quarter-final after a crushing seven-wicket defeat of struggling Worcestershire.

The 30-year-old made light work of a sluggish Northampton track to inflict the damage on his former employers - sealing the Steelbacks' seventh win of an impressive Twenty20 campaign.

South African Andrew Hall had earlier wreaked havoc with the ball for the home side, picking up four wickets for 19 runs from his four overs - with just three Worcestershire players reaching double figures.

However, Peters stole the show with his 61 - including six fours - booking the Steelbacks a spot in the last eight for the fifth time in as many years.

The visitors found themselves under pressure from the outset with Hall and Johannes van der Wath celebrating the pre-match award of their county caps with an early wicket apiece.

Royals skipper Vikram Solanki departed first, dragging the ball into his stumps, before an all-South African dismissal saw Stephen Moore smartly stumped by Riki Wessels from Hall's first ball.

Steven Davies, who had batted promisingly for 26, was the next to go after holing out at deep cover from David Willey's first ball.

And when Ben Smith was leg before wicket sweeping Nicky Boje, the visitors were struggling at 53 for four at the midway point of their innings.

After Daryl Mitchell ran himself out, Moeen Ali and Ashley Noffke added 35, including the innings' only six, struck over long-on by the Australian.

However, both batsmen fell in the deep to the returning Hall, Moeen for an uncharacteristically sedate 28, as the visitors paid the penalty for 10 overs without reaching the ropes.

Hall was the star of the show finishing with four wickets and with Willey, van der Wath and Boje all chipping in with a wicket apiece as the Steelbacks barely missed Australian all-rounder Ian Harvey - resting a finger injury.

The home reply began badly when Rob White edged Noffke behind in the third over - Davies holding on to the chance.

And when Willey and Wessels both fell to the former Yorkshire combination of Gareth Batty and Ian Fisher, Northamptonshire were wobbling at 44 for three in the ninth over.

But it was 30-year-old opener Peters who stopped the rot and settled in for the anchor role and ensured there were no further mishaps.

Alex Wakely joined the former Essex opener in a match-clinching fourth wicket partnership of 66.

His rapid 29 from 23 balls included the stroke of the day, a straight drive rifled off the bowling of Chris Whelan - and the pair saw the Steelbacks home with two overs to spare.