DERBY County eased into the fourth round of the FA Cup with a 5-0 victory over League One leaders Tranmere Rovers at Pride Park Stadium.
Ben Davies broke the deadlock just before the interval and the Rams took control with second-half strikes from Conor Sammon, John Brayford, Jeff Hendrick and 16-year-old substitute Mason Bennett, who netted his first senior goal to become the club's youngest ever scorer.
Gareth Roberts returned to the Derby side to face his former club.
The 34-year-old defender missed the 3-1 victory over Middlesbrough on New Year's Day due to a calf injury but was passed fit to replace Kieron Freeman at left-back in the only change to Nigel Clough's starting line-up.
Midfielder Craig Bryson (knee) and Jamie Ward (hamstring) remained sidelined.
Derby had a couple of early scares.
In the fourth minute, defender Ash Taylor headed wide from an inswinging corner.
And six minutes later, midfielder Max Power harried Davies off the ball and, spotting Adam Legzdins out of position, shot from 20 yards, but the keeper got across to make the save.
Brayford glanced a header wide from Davies' corner after 26 minutes.
And the hosts had a chance to test keeper Owain Fon Williams soon after when he inadvertently picked up a backpass from Donervorn Daniels in his area but the defensive wall blocked Michael Jacobs' strike.
The Rams went ahead shortly before the interval.
Paul Coutts' shot from the edge of the box squirmed under the body of Fon Williams and the ball rolled towards the goal.
Davies won the race with Taylor to get there first and prodded home from a couple of yards out.
Derby's second goal arrived less than 10 minutes into the second half.
Davies' free kick from the right was attacked by Richard Keogh and the ball bobbled around in the box until it reached Sammon, whose shot on the turn went in via a deflection.
Moments later at the other end, Cole Stockton cut in from the left before blasting narrowly over from a tight angle.
Jacobs tested Fon Williams with a dipping 25-yarder which the keeper turned around the post.
Brayford attempted to get on the end of Davies' resulting corner, only to end up on the floor.
However, after a bit a pinball in the area, the defender was able to hook a shot past Fon Williams from six yards, from a sitting position.
It was 4-0 after 72 minutes, when Hendrick controlled Davies' ball in with his left foot and finished clinically with his right foot, low into the corner of the net from 18 yards.
Tranmere might have pulled one back with 15 minutes to go when Adam McGurk's corner found Zoumana Bakayogo unmarked in the middle but the defender blazed a volley way over the bar.
Derby got a fifth goal in the 87th minute when Conor Doyle set up fellow substitute Bennett, whose crisp low drive from the edge of the box went in, despite a touch from Fon Williams.
GOALS: Davies (43) 1-0; Sammon (54) 2-0; Brayford (63) 3-0; Hendrick (72) 4-0; Bennett (87) 5-0.
DERBY COUNTY: Legzdins, Brayford, Keogh, O'Brien, Roberts (Freeman, 74), Coutts (Doyle, 79), Hughes, Hendrick, Davies (Bennett, 85), Jacobs, Sammon. Other subs: Fielding (gk), O'Connor, T Robinson, Tyson.
TRANMERE ROVERS: Fon Williams, Holmes, Daniels, Taylor, Bakayogo, McGurk, Palmer, Power, A Robinson (Black, 73), Stockton, O'Halloran. Other subs: Mooney (gk), Goodison, Thompson, Harrison, Kirby, Kay.
REFEREE: M Halsey (Lancashire).
ATTENDANCE: 11,740.
