Michael Doyle is confident the Blades will not underestimate Cambridge United in Sunday's FA Cup second round tie.
The skipper issued a warning to his team-mates ahead of the clash at The R Costings Abbey Stadium, remarking:
"These are the games where, if you're not completely at it, then you are going to get found out.
"You've got to relish these situations and be right 'on it' because character could well be the key."
United's captain has history of being part of a giant-killing. Doyle was part of the Leeds team, along with Aidy White, that humiliated Manchester United at Old Trafford 2010, he added:
"That was a third tier team beating one of the best in the country so it just goes to show what can happen in the cup.
"But there won't be any problem, for me, with our attitude because there's a good feeling around the place at the moment with everyone working together.
"There's just this sense that we're all pulling in the same direction and that we're a close knit team.
"There are a lot of positives for us to build on, including coming out of a very important week with games against Bristol City, Walsall and Leyton Orient unbeaten."