Usama Mir, making his Rapids debut as short-term cover for the incoming Mitchell Santner, bamboozled Northamptonshire's home batters to finish with figures of 3 for 21
Northampton: Worcestershire 196-9, Northamptonshire 181-8 - Worcestershire win by 15 runs
Leg-spinner Usama Mir ruined David Willey's Northamptonshire homecoming with a decisive spell to guide Worcestershire Rapids to victory in their Vitality Blast opener at Wantage Road.
The Pakistan white-ball international, making his Rapids debut as short-term cover for the incoming Mitchell Santner, bamboozled the home batters to finish with figures of 3 for 21.
Willey, who re-joined the Steelbacks after a seven-year stint at Yorkshire and was recently appointed T20 captain, looked set to lead his side to victory with 36 from 24 balls as they chased Worcestershire’s total of 196 for 9.
But Mir's introduction triggered a Northamptonshire collapse as five wickets tumbled for 26 and fellow leg-spinner Brett D'Oliveira chipped in with three for 28 to restrict the hosts to 181 for 8.
Worcestershire, who finished bottom of the North Group last season with just two wins, won the toss and batted but were soon in trouble as Tom Taylor (3 for 42) removed both openers in the powerplay.

David Willey was back for Northamptonshire (David Rogers/Getty Images)
Having swung Taylor for the first six of the night, Michael Bracewell attempted a repeat to a slower ball and picked out deep square leg, while Rapids skipper D'Oliveira lost his middle peg going for the scoop.
Jack Haynes began the rebuilding job, finding the boundary regularly in his 27 from 17, but he and Kashif Ali (16 from 12) were both caught in the deep off miscued shots and it was left to Adam Hose to underpin the innings with a knock of 61 from 40.
The Rapids batter was handed a life on 43, driving James Sales to mid-off where Willey fumbled the catch and went on to complete his half century from 34 deliveries by leg-glancing AJ Tye to the boundary.
But Hose eventually perished in controversial circumstances, skying a Graeme White full toss that looked high enough to enter no-ball territory and the bowler sprinted towards midwicket to complete a sprawling catch.
Ed Pollock maintained momentum, clubbing Taylor for two sixes in his 23 from 11 and Mir slammed an unbeaten 20 from only seven balls before the innings closed with two run-outs – one a deft piece of fielding by Willey off his own bowling to remove Adam Finch.

Worcestershire got off to a winning start (David Rogers/Getty Images)
The Steelbacks were handed a bonus at the start of their reply, with Mitchell Stanley's first three balls going for wides down the leg side, but they soon began scoring freely off the bat as well.
Ricardo Vasconcelos brought out the paddle shot to good effect against Finch before Chris Lynn came to the party, punching four consecutive boundaries off Bracewell to bring up 50 at the start of the fifth over.
Having reached 28 from 14, Lynn immediately holed out to Stanley, but Willey announced his arrival at the crease in dramatic fashion, dispatching Pat Brown for 14 in three balls and then hoisting Finch for two colossal sixes.
Northamptonshire looked comfortable at 90 for 1, but Mir struck with his fourth delivery, bowling Vasconcelos for 32 and, when Josh Cobb speared Brown to extra cover in the next over, the pendulum tilted towards the visitors.
Saif Zaib and Rob Keogh fell to Mir, while Willey was taken on the boundary off D'Oliveira and, despite Taylor's valiant unbeaten knock of 44 from 26, it was not enough to save the Steelbacks.