Derby thrash Hull to shake up Championship promotion picture
Hull's hopes of automatic promotion were dealt a hammer blow when they were beaten 4-0 by Derby, who got their play-off challenge back on track.
The visitors had controlled the game until a slip by Curtis Davies in the 24th minute allowed Bradley Johnson to score and after the midfielder added a second before the break, Hull had Moses Odubajo sent off for bringing down former Tiger Tom Ince in the 55th minute.
Chris Martin finished Hull off with his 15th of the season and then set up Craig Bryson for a fourth in stoppage time as Derby equalled their biggest win of the season.
There had been no sign of what was to come as Hull started confidently, with Odubajo dragging a shot wide before Scott Carson tipped over a Sam Clucas header and then saw a 25-yard shot from the midfielder go narrowly wide.
Hull had looked comfortable but a slip out on the left by centre-back Davies in the 29th minute changed the game as Bryson raced clear and although Martin turned his cross against a post, Johnson slammed in the rebound from six yards.
If there was a large slice of luck involved, there was nothing fortuitous about Johnson's second in the 38th minute which came after a clever interchange of passes out on the Hull right.
Johnny Russell flicked the ball inside to Ince and his back-heel was met first time by Johnson, who fired the ball low past McGregor from 10 yards.
It was deja vu for Hull, who conceded twice in the first half against Derby at the KC Stadium in November, and they again had a lot to do to get back in a game they had controlled.
Former Derby midfielder Tom Huddlestone skied a shot over from just outside the area early in the second half and manager Steve Bruce made his intentions clear when he brought on striker Abel Hernandez in the 50th minute.
But it went from bad to worse for Hull five minutes later when Odubajo was shown a straight red card for bringing down Ince just outside the area when he was through on McGregor.
With Hull down to 10 men and chasing the game, Derby almost scored a third when Cyrus Christie jinked his way into the area but could not keep his shot down.
Hull were down but still not out as Clucas showed in the 74th minute with an acrobatic volley at the back post that brought a superb reaction save from Carson.
Minutes later, McGregor did well to block a Martin header - but Martin made the game safe in the 84th minute when he brought down a ball on the edge of the area and turned to score with a left-foot strike.
He then crossed for Bryson to put the gloss on a memorable night for Derby.