Sheffield Wednesday boss Dave Jones remained optimistic on Championship survival despite a 1-0 defeat at fellow-strugglers Peterborough.
A magical finish from Grant McCann earned three priceless points for the hosts who keep out of the drop zone on goal difference.
But with Wednesday one point above the relegation spots with only a game remaining, their hopes are still good.
"There are several teams still in danger but our destiny is in our own hands and that is what is important," Jones said. "We're not in the position of having to rely on other results.
"Staying in this league will be a far bigger achievement than winning promotion last season to get here."
It was McCann's stunning curling free-kick in the 64th minute that separated the sides, with the visitors struggling to provide any resistance.
"There were a lot of nervous people out there on the pitch and it was always going to take something special to win the game," Jones added.
"We didn't do any better or worse than Peterborough did, but they had that one moment that mattered. It was sloppy on our part to concede the free-kick.
"We decided to play a system that has brought us success away this season, but unfortunately that wasn't the case today. We had a couple of chances but their keeper saved one and we should have done better with another."
The Robins will now play Northampton Town over two-legs with the Bantams facing Burton Albion with a place in the Wembley play-off final at stake.
"Bradford are a really, really good side - they got to the final of the Carling Cup - so I'm not too disappointed that we won't be playing them," Yates said.
"That's no disrespect to Northampton who are also a good team with a top manager but Bradford are a really good team.
"We are in the play-offs and that's a great achievement for the players on the back of the disappointment of last year. We have to use that in a positive manner to make sure that we are as good as we can be on Thursday and as good as we can be on the following Sunday.
"The league doesn't lie after 46 games and we are right up there with the best. We can be a little bit disappointed today because we have not got that third spot but we need to go back to work and get ready to go again. It just wasn't our day and Marlon [Pack] summed things up when he hit the post - not that it would have mattered.
"If you get 20 clean sheets then you should be getting automatic promotion but it's a strange league this year. It has been really tight from top to bottom."
The 37-year-old marked his 395th and last League game with a penalty and a typically clinical finish after Jay O'Shea and Marc Richards had opened the scoring.
Chesterfield assistant manager Tommy Wright said: "I think the players wanted to win it for Jack. It was great for him to score two goals and I don't think the script could have been better with him getting our first penalty in the league this season and dinking it like Panenka the Czechoslovakian.
"It was a great day and it's a credit to all the players that they put on a performance like that for a great professional and a good man. He's been a model professional, he's always wanted to play every game. He's been a great finisher and I'm sad to see him go."
Chesterfield had been tipped as one of the favourites for promotion and Wright admitted: "In the last six or seven weeks the form has been quite good but the league doesn't lie.We have good players at the club and everyone should be optimistic for the coming season."
Veteran striker Jack Lester rounded off his career with a brace, while Jay O'Shea and Marc Richards also got in on the act.
"I'm really pleased with the way those young players played," Tisdale said.
"I think it's a sign of things to come over the next 18 months or two years.
"It was a good opportunity to see them play, we were a bit nieve at times and a little bit too nice in some areas of the pitch but
I really enjoyed the game.
"It's never nice to lose a game of football and 4-0 doesn't look good but I'm really pleased with some of the players and we are making progress.
"It was an opportunity for them to play and for me to see how they make decisions in this sort of situation and I've learnt a lot from the day.
"We are going to have to bring some of these players through and they are not going to win games straight away."
