Chesterfield manager Paul Cook believes the rest of League Two are starting to take notice of his side.
The Spireites have surged up the table in the past month thanks to a five-game unbeaten run consisting of four wins, including victories over two of the top-three in the shape of Cheltenham and Port Vale.
Cook takes his side to sixth-placed Southend, who are unbeaten in 12 matches in all competitions, on Friday night looking to claim another of the division's top scalps.
He told Press Association Sport: "I think we've sent a couple of warning signs out recently.
"We've got good players at Chesterfield, we're a very strong team. There's a long, long way to go this season and we've got a lot to play for and we're happy to go with any team in this league and have a football game.
"Southend is another tough game. They're in good form, they're a very strong club at League Two level, they've got play-off experience and they've got a lot of experienced players. But we'll go there to win the match, as we always try to do.
"It will be a tough game for us but it will also be a very tough game for Southend."
Victory at Roots Hall would see Chesterfield go above Southend in the table and into the play-off places ahead of Saturday's fixtures.