Phil Parkinson believes his Bradford City side are capable of beating any team, on any ground.
Sunderland became the latest Premier League side to fall foul of the Bantams on Sunday, losing 2-0 at Valley Parade after Chelsea had succumbed 4-2 at Stamford Bridge in the Fourth Round.
And as attention turns to Monday night’s quarter-final draw, Parkinson has backed his League One side to take on anyone.
Bradford City 2-0 Sunderland
The FA Cup
Fifth Round Proper
Sunday 15 February 2015
Valley Parade, Bradford
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"If we get our approach right we've got a chance against anybody, and we proved that today,” he said.
"There was always a danger that, because we beat Chelsea, everyone would expect us to win today, and we had to guard against that and go in there with the underdog mentality.”
They did that from the off, opening the scoring with a deflected Billy Clarke effort, and when Jon Stead doubled the advantage against his former club, the Black Cats had rolled into a ball.
"Right from the first whistle we played with great desire and great spirit and we were first to every ball all over the pitch,” said Parkinson, who took over at Valley Parade with the club close to the bottom of League Two.
"Maybe we took Sunderland by surprise. We made it an uncomfortable afternoon for them, which you've got to do against a top side.
“Our second goal was great and we killed the game off in the late stages.”
Parkinson said a sell-out home crowd played a major part in the upset.
He continued: "Today is another terrific day and to have Valley Parade full of 24,000 fans it's like a throwback.
“The lads were absolutely revelling in it and they deserve the support because of their performances and the effort they have put in over the years."
Sunderland boss Gus Poyet was honest in his appraisal of Bradford, and refused to blame the boggy Valley Parade turf for his side’s failure to progress.
"I'm not going to complain about the pitch - we didn't lose because of the pitch,” he said.
"Bradford won at Stamford Bridge on a great pitch and today they played here and beat us on this pitch so you need to give plenty of credit to what they do."
The Uruguayan – who went into the fixture without the injured Jermain Defoe – added: "We tried our best and I think no regrets because everybody put in their best effort and their best ability to play under the circumstances.”