Jamal Blackman believes the strength of United's goalkeeping department has aided the team this season.
Both Blackman and Simon Moore have had stints as Chris Wilder's number one this season, with the Chelsea loanee returning to the starting XI against Millwall, having served a three-match suspension following his red card at Brentford last month.
And the imposing stop says the competition is health, he remarked: "I've been working hard behind the scenes since Brentford and I've been pushing Simon all the way.
"We all want to do our best and help this club get into the play-offs, so it's great for me to be back playing again.
"We always push each other, regardless of who has the shirt and it brings out the best in each other, even though you're fighting for that one spot."
On the race for the top-six, Blackman added: "We've got three winnable games and we believe we can win all three matches.
"It's so tight at the top, we still believe we can make it and that belief won't change."