The Blades blister fully eased there way through into the second round and could potentially face a Premier League club in the next round; they won't however have the lottery of facing Manchester United, Arsenal, Liverpool or Chelsea as Champions League clubs won't enter this competition until the third round.
Sheffield United manager Bryan Robson, as we expected made wholesale changes to the squad that drew 2-2 with Colchester United last Saturday. A similar side was fielded with the notable inclusion of Australian David Carney who was making his full debut following his £50,000 move from Sydney FC this summer.
Bryan Robson opted to give James Beattie and Billy Sharp the night off with Jonathan Stead and Danny Webber taking their places; and his shrewd thinking paid dividends as both rewarded the new manager with goals.
The lead came after just 15 minutes when Webber cut inside and drilled the ball at goal, Barry Roche pared to the path of Stead who turned and fired into the goal.
And, like last Saturday the lead only lasted one minute when a Spirites attack found former Blade Jack Lester wheeling away in celebration. Peter Leven pounded the ball into the box and Lester headed home out of Kenny's reach.
Alan Quinn, who had earlier replaced Gary Naysmith almost put United back in front after 36 minutes; Stead set up the former Wednesday man but Quinn's effort was pushed round the post.
Just before the stroke of half-time United made it 2-1, Leigh Bromby pumped a long ball forward and was brought down by Stead who latched and finished from 10 yards.
Chesterfield made United fight all the way to the bitter end and another former Blade Wayne Allison almost levelled, the Chief stretched to meet Phil Picken's cross but his header was blocked on the line by Kenny.
And, four minutes later Danny Webber raced through to smash the ball home to give United a 3-1 lead and place in next rounds League Cup.
New signing David Carney was set up by Derek Geary late on but failed to hit the target.