Brentford bought their ticket for the £140million play-off lottery after a 3-0 win against Wigan, while Derby and Ipswich fell to defeats.
In a day of high drama, the Bees did their job as goals from Alex Pritchard, Jota and Andre Gray gave Mark Warburton's side a chance to secure a chance of promotion to the Premier League.
There was even time for James Tarkowski to miss a penalty as Derby crashed to a 3-0 defeat at home to Reading.
"I'm delighted for the players and supporters," said manager Mark Warburton. "We always said where can we be by May 2, and here we are in fifth. To play that way and for results to go our way is very pleasing.
"We spoke to players on June 25, the first day of pre-season training, and told them we had no doubt where we could go. And they've achieved it."
The Bees will face Middlesbrough in the play-off semi finals with the first leg on Friday night and the second the following Friday.