Martyn Waghorn headed Derby ahead against West Brom
Derby County secured a Championship play-off place as two goals in three second-half minutes secured victory over West Brom.
The Rams needed a win to be certain of a sixth-place finish against a side who were already assured of ending their campaign in the top four.
Middlesbrough did beat Rotherham to ensure Frank Lampard's side had to take all three points, and they did so in fine style at a packed-out Pride Park.
Martyn Waghorn's perfectly placed near-post header from Jayden Bogle's exquisite cross earned the hosts a half-time lead in an open game.
The Baggies deservedly levelled two minutes after the break through Stefan Johansen's superb curled strike.
But Derby dominated from then on.
Substitute Mason Bennett's close-range finish two minutes after coming on made it 2-1 after 70 minutes and Harry Wilson's penalty sealed the victory.
West Brom, who would have finished third with victory, as a result of Leeds United's unexpected defeat against Ipswich, had substitute Hal Robson-Kanu sent off in stoppage time for kicking out at Bradley Johnson.
Derby will face Leeds United, who beat them in both league games this season, in the two-legged semi-final, while West Brom meet fierce local rivals Aston Villa.
Lampard (right) enjoys the feeling of a top-six finish with assistant boss Jody MorrisLampard leads the way
The Rams have become accustomed to play-off heartache in some form or another over the past few seasons.
They suffered an agonising last-minute Wembley defeat in the 2013-14 final against QPR, missed out on the top six on the final day of the following season and have been beaten in two of the past three play-off semi-finals since.
But their performance against the Baggies was both stylish and brave, and their place in the top six in Lampard's first season was fully merited after a fine season and this impressive display.
Jacob Murphy and Dwight Gayle missed glorious chances for the visitors either side of Waghorn's stunning opener.
But after Johansen's classy finish made it 1-1, Derby seized control.
With home pressure building and Mason Mount, Tom Lawrence and Wilson particularly impressive, Bennett followed up to poke the Rams back in front on the rebound.
And Wilson's penalty after Lawrence was deemed to have been fouled by Kyle Bartley after a mazy run, brought a 3-1 lead which was comfortably kept.
Baggies demonstrate attacking quality
Despite their defeat, the Baggies created the better chances until soon after Johansen's strike and looked sharp for their mouthwatering semi-final date with Aston Villa.
A peculiar season saw Darren Moore sacked as manager in March with the Baggies fourth, but nine points off the top two following a 1-1 draw at home against bottom-of-the-table Ipswich.
However, a run of six wins in 10 matches under caretaker-boss Jimmy Shan confirmed their top-six finish and they face Villa in encouraging form, led by a front pairing of Gayle and Jay Rodriguez who have 45 goals between them this season.
