A slick Brighton & Hove Albion performance pushed them nine points clear of third place in the race for the automatic promotion places in the Championship.
The Seagulls brushed aside a below-par Derby outfit thanks to first-half goals from Anthony Knockaert and Sam Baldock and a Glenn Murray strike after the break to go level on points with leaders Newcastle United.
It saw Chris Hughton's side register back-to-back wins after their blip against Newcastle United and Nottingham Forest and go clear of Huddersfield, who face Brentford on Saturday and have an extra game in hand.
Albion made one change from the side that won at Rotherham on Tuesday night as Murray came in to the starting 11 for Tomer Hemed. While Chuba Akpom returned to the bench after a knee injury had ruled him out of the last two games.
Derby boss Steve McClaren meanwhile plumped for an attacking line-up and named four strikers in Darren Bent, Matej Vydra, Tom Ince and David Nugent in his starting line-up.
The home started with a real fluency within their play and crisp sharp passes flew around on the slick surface. It was in the fourth minute that Knockaert set Jiri Skalak away and he cut inside and flashed his right-footed shot just wide.
Albion led just a minute later as Knockaert skipped past a challenge, steadied himself and sent a low effort into the bottom corner from 22 yards.
The Rams' first chance came on seven minutes as a Cyrus Christie cross from the right picked out Bent, but the striker's downward header bounced up and over the bar.
Derby goalkeeper Scott Carson then collided with team-mate Jacob Butterfield as Murray attempted to latch onto a Baldock pass, but the former England stopper was able to continue after treatment.
Lewis Dunk then had his penalty claims waved away as Alex Pearce was clearly holding his shirt in the penalty area from a set-piece delivery.
On 23 minutes, a neat Dale Stephens backheel put Knockaert away and he slipped in a ball behind for Baldock, but his angled effort was deflected behind.
Carson then turned behind twice in quick succession from an Uwe Huenemeier cross and Knockaert corner, before a Lewis Dunk header landed on the roof of the net.
The pressure finally told two minutes before half-time, some cool defending from Dunk at the back was the foundation for the attack and Murray found himself with the ball in the box, but it came off a defender and into the path of Baldock, who slotted past Carson.
And it should have been 3-0 a minute later as Baldock flashed another effort across goal and just wide moments before the break.
After a poor showing in the first half, Derby made two changes as the break as Craig Bryson and Will Hughes replaced Julien de Sart and Nugent.
It made little difference and Albion were soon into their stride as a powerful first-time hit from Knockaert was pushed over the bar by Carson.
Skalak's first-time cross towards the back post was headed down by Dunk and Carson was forced to push away the bouncing ball.
In a rare Derby attack just past the hour mark, Christie's cross was met by Vydra, but his header clipped the outside of the post.
Albion added a third on 78 minutes as a ball from a free kick flew all the way in behind and Knockaert flicked the ball across the box for the arriving Murray, who finished with aplomb past Carson.
Brighton: Stockdale, Bruno (Tomori 65), Huenemeier, Dunk, Rosenior, Knockaert (March 82), Stephens, Kayal, Skalak, Murray (Hemed 79), Baldock. Unused subs: Walton, Sidwell, Norwood, Akpom.
Derby County: Carson, Christie, Pearce, Bard, Olsson, de Sart (Hughes 46), Butterfield, Vydra, Ince, Bent, Nugent (Bryson 46). Unused subs: Mitchell, Russell, Anya, Lowe, Bennett.
Attendance: 27,552 (1,107 away).
Referee: Chris Kavanagh.