Chris Wilder has been appointed Northampton Town manager on a three-and-a-half-year deal after quitting League Two rivals Oxford United.
for Wilder's departure on Sunday.
It means the 46-year-old, who will be assisted by Alan Knill, will be leaving the sixth-placed U's for a team 23 points further down the table and bottom of the Football League.
"It was a difficult decision," he told BBC Radio Northampton.
"I think people can look at the job I did at Oxford and say it was a decent job in terms of where it was and where it is now.
"I want Northampton's players to look forward to the challenge. We're in a position where perhaps a lot of people have written them off - it's Northampton and one other going down.
"It's up to me and the players to change that."
Wilder added that will not be looking to recruit players from his former club.
Northampton had been managerless for five weeks following with Andy King, who has now left Sixfields, taking caretaker charge.
Oxford had rejected an official approach from Northampton on Friday but chairman Ian Lenagan said on Saturday that he understood Wilder had decided to quit, before the former Halifax boss later denied that was the case.
But the U's accepted Wilder's resignation on Sunday after a compensation package was agreed and he will lead out the Cobblers against Rochdale on Tuesday.
Wilder, who was set to be out of contract this summer, will now turn his focus from a promotion campaign to a relegation battle.
Chairman David Cadoza said: "I apologise that it's taken this long. But I'm certainly not apologising that it's taken this long to find the right person.
"A lot of people have tried to bully me, belittle me, force me into a decision before I'm ready to. The majority of the fans, I think, are behind me.
"We'll get the players in to make the difference.
"We've paid significant compensation to Oxford, significant compensation to Aidy Boothroyd and now we're going to sign a few more players. It's a very expensive job.
"I would expect anything up to four or five players coming in."
Former Sheffield United and Rotherham defender Wilder was named U's boss in 2008 and went on to win promotion from the Conference Premier in the 2009-10 campaign, his first full season in charge.
Since then, Oxford have stabilised as a League Two side, and they are two points off the automatic promotion spots.
Former Scunthorpe manager Knill joins Wilder's backroom team after being earlier this month.