Barnsley are in the best position out of the three clubs scrapping for the final play-off place on the last day of the season, insists Paul Heckingbottom.

The sixth-placed Reds travel to champions elect Wigan Athletic on Sunday for a 12.30pm kick-off. They need to match the results of seventh-placed Scunthorpe and eighth-placed Gillingham in order to book a place in the play-offs. Barnsley's recent away record is excellent – they have won eight and lost one of the last 12 on their travels – and they have filled 35 free supporters' coaches while they are expecting to sell out the ticket allocation of 4,929.

"We were hoping to have a chance going into the last game and now we do," said Heckingbottom.

"I would rather be in the position that we are in. I am delighted that we have come this far and got ourselves in the mix. Now it is about finishing the job and it's come down to one 90-minute game.  That was what we were always dreaming about and hoping for."

Wigan have already secured promotion back to the Championship at the first attempt and are almost certain to finish first as their goal average is 20 better than second-placed Burton who are three points behind them. Barnsley have never beaten the Latics in the league and have lost six of their last seven meetings in all competitions with the exception being the Johnstone's Paint Trophy penalty shoot-out victory at the DW Stadium in December.

The Latics – who then won 2-0 at Oakwell in the league two weeks later – are the top-scorers in the division while they have lost by far the fewest games with only six defeats from 45. They have League One's best home record and have not been beaten at the DW Stadium in 11 games since December. They surprisingly lost for the first time in 20 matches at lowly Doncaster last month but have scored four in each of their last two matches and earned promotion on Saturday.

Heckingbottom said: "Wigan are the champions and they were the best team we have played this season when they came to Oakwell. But they are not invincible.

"We played well against them in the cup and that's something we have to take heart from. Our away form has been good and we will cause any team problems away from home. We know it's a big challenge but we have to embrace that.

"I think we will have about 4,500 fans there which is amazing. The fans have been part of this ride and they will be a big part of the occasion on Sunday.  The atmosphere is going to be fantastic. Wigan will be celebrating being champions and we are going there to get into the play-offs."

Scunthorpe's final game is at mid-table Sheffield United while Gillingham host fourth-placed Millwall. Heckingbottom says his coaching staff will be passing information about the scores at Bramall Lane and the Priestfield Stadium onto the pitch later in the match. He said: "We will want ears and eyes everywhere.  Our outlook won't change until the final 20 minutes or so and we have to make sure we are in a good position in our own game by then. We will plan to go and win the game but we will look at other scores later on and adjust accordingly.  With 20 minutes left we might be drawing and need to win, or losing and need to draw or winning and need to consolidate. We just need to make sure we are in the picture on 70 minutes."

Barnsley would be in a more comfortable position had they not conceded a late equaliser against relegated Colchester on Saturday. Heckingbottom has played down suggestions that Wigan may not be at their best as they are already promoted. He added: "I heard last week that it was a good thing Colchester had gone down. It's daft, you can't think like that. You can't expect anyone to do us any favours.

"I could feel before Colchester that everyone had given us the three points and I couldn't stand it.  Now I feel we have been written off because we have the champions away from home. That might work in our favour."

Wigan have League One's top-scorer, 27-goal Will Grigg, while their other attacking stars are midfielders Yanic Wildschut, Michael Jacobs and Max Power. The Latics also have several ex-Reds. Right-back Reece Wabara spent the first half of this season at Oakwell before his contract expired in January and he moved to the Latics, where he has impressed and become a regular. Midfielder David Perkins – who played 100 games for the Reds between 2011 and and 2014 – has played 44 of Wigan's 45 league matches this season.

Perkins was announced as Wigan's Player of the Year on Wednesday. His former Oakwell colleague Craig Davies has struggled for a place in the side, scoring twice in 30 games.