Scunthorpe must go to Chelsea believing they can win their FA Cup third-round tie, according to defender Scott Laird.
The Iron beat Leyton Orient 3-0 in their second-round replay at Glanford Park on Tuesday to set up a trip to the Premier League champions in January.
Jose Mourinho's side have lost four games at Stamford Bridge this season.
"It is a great opportunity and we have got to go there believing we can win. The FA Cup is made for upsets," Laird told BBC Radio Humberside.
"I was part of a Stevenage team that beat Newcastle and took Tottenham to a replay," he added. It's doable, they're only human.
"I'm sure they'll be looking to win the FA Cup because it looks like their only hope [of a trophy] at the moment.
"It's a great chance for us to go there and play with the shackles off because nobody is going to expect us to win but you saw what Bradford did there last year."
Laird put Preston 1-0 up in their FA Cup fifth-round tie against Manchester United last season before the Red Devils came back to win 3-1.
He believes the forthcoming tie with the Blues, who are understood to be considering the future of boss Mourinho after their poor start to the season, can be a catalyst for an improvement in the club's league form.
Mark Robins' side are currently 14th in League One, seven points off the play-off places.
"We've got a great squad of players and I think second half we really showed how well we can play football," Laird added.
"We've got to start producing on the pitch now and everyone should be at it 100% to stake their claim for a shirt for the Chelsea game."