Charlton win 4-3 on penalties
Scott Carson saved two penalties to end Chesterfield's Carling Cup dream and take Charlton into the quarter-finals for the first time in their history.
Charlton players celebrate after their shoot-out victory
Chesterfield led through Colin Larkin's close-range strike but Jimmy Floyd Hasselbaink's low shot made it 1-1.
Caleb Folan headed in another corner to make it 2-1 but Darren Bent's clever deflection forced extra-time.
Another Hasselbaink shot put Charlton ahead but Wayne Allison's header forced penalties and Charlton edged through.
Roy McFarland's Chesterfield had already beaten Manchester City, Wolves and West Ham to reach the last 16 and raced ahead after three minutes.
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Larkin reacted first to Kevan Hurst's corner and half-volleyed the ball home via the underside of the bar.
Andy Reid went close for the Addicks but the Spireites were the better side before the break and Folan and Hurst were posing the visitors' defence no end of problems.
Larkin almost made it 2-0 with a 20-yard drive and Hurst sent a fierce shot narrowly wide after a well-worked free-kick.
But in the 40th minute Hasselbaink was allowed too much space on the edge of the box and fired a low left-foot shot past Barry Roche.
Colin Larkin (left) jumps for joy after his early goal at Saltergate
Chesterfield responded after the break in fine style when Folan's glancing header beat Carson from six yards.
It was no more than the Spireites deserved and Charlton were forced to summon England striker Darren Bent from the bench.
The decision paid dividends when Bent's quick reaction's saw him divert Jerome Thomas' shot past Roche
And Iain Dowie's Premiership strugglers looked to have won it in extra-time when Hasselbaink combined with Thomas to finish low past Roche.
But McFarland's gallant side were not to be denied a chance at penalty glory and veteran striker Allison came off the bench to head home at the far post.
However Carson was the hero from 12 yards, saving efforts from Derek Niven and Mark Allott.
Chesterfield manager Roy McFarland:
"It was a fantastic fooball match.
"Sadly we've gone out on penalties but we've given everything and I think we've matched them.
"Three Premiership teams haven't been able to beat us in 90 minutes and we're proud of that."
Charlton boss Iain Dowie:
"I'm delighted with the spirit and effort of the boys, we matched them all the way.
"That's what you have to do on nights like this. They made us work for every inch and we have just sneaked through.
"When they got the late goal I wondered if it was going to be our evening."
Chesterfield: Roche, Lowry, Hazell, Downes, O'Hare, Hall (Smith 91), Niven, Allott, Hurst, Larkin (Davies 115), Folan (Allison 85).
Subs Not Used: Jordan, Kovacs.
Goals: Larkin 3, Folan 47, Allison 120.
Charlton: Carson, Young, Diawara, Fortune, Hreidarsson, Hughes (Ambrose 65), Kishishev (Faye 75), Reid, Thomas, Marcus Bent (Darren Bent 65), Hasselbaink.
Subs Not Used: Andersen, Sankofa.
Booked: Fortune, Faye.
Goals: Hasselbaink 40, Darren Bent 73, Hasselbaink 93.
Ref: M Riley (W Yorkshire).