Barnsley lost 1-0 at home to Swansea City in the first leg of their play-off semi-final at Oakwell on Monday evening.
The hosts took the lead near the end of a first half of few chances then the Reds were far better in the second half but missed key chances.
The second leg is at Swansea on Saturday at 6.30pm.
Valerien Ismael made three changes to the side that drew 2-2 with Norwich City in the last league game nine days earlier. Alex Mowatt returned to the side in place of Jasper Moon while Daryl Dike and Dominik Frieser replaced Carlton Morris and Conor Chaplin.
Swansea lined up in a 4-3-3 formation with former Reds captain Conor Hourihane one of their central midfielders while forwards Jamal Lowe and Andre Ayew, who caused the Reds problems in the two league wins for Swansea this season, were the wide forwards either side of Liam Cullen.
There were about 4,500 fans at Oakwell as supporters were allowed to attend for the first time since March last year. There were plenty of powerful moments before kick-off with the supporters reacting to the entrance of Ismael and his players.
Romal Palmer had the first shot of the game, curling over from just outside the box in the fifth minute.
Barnsley shaded most of the first half, without creating any real chances, then Swansea took the lead in the 38th minute.
Andre Ayew latched onto a pass by Kyle Naughton on the right of the box, cut past Michal Helik and bent a fine shot into the bottom left corner.
Barnsley responded well and almost levelled but Helik headed Palmer's right-wing cross too close to goalkeeper Freddie Woodman who saved.
Frieser was replaced at half-time by Morris whose shot was spilled by Woodman and Callum Brittain should have scored his first Barnsley goal but put his close-range rebound too close to the goalkeeper who made a fine save.
The Reds were on top early in the second half, with Woodrow's free-kick also saved by Woodman diving down to his left then the impressive Morris sliced a 15-yard volley over the bar.
Barnsley then had several men over on the counter-attack after a corner was cleared, but Dike's pass was just in front of Morris who would have been clean through on goal.
Dike's good pass almost put Morris through but Woodman just got there first then, at the other end, Lowe twice beat Toby Sibbick before curling wide from the right of the box.
Matt Grimes' 25-yard swerving effort was beaten away by Collins in the 85th minute. The Reds almost levelled in the 93rd minute when Woodrow's low left-wing corner was cleverly flicked by Morris and it looped onto the crossbar.
Barnsley (3-4-3): Collins; Sibbick, Helik, Andersen; Brittain, Mowatt, Palmer (J Wiliams 79mins), Styles; Frieser (Morris HT), Dike (Adeboyejo 88), Woodrow. Unused: Walton, Kitching, Chaplin, Halme, Sollbauer, Moon.
Swansea (4-3-3): Woodman; Naughton, Guehi, Cabango; Fulton, Grimes, Hourihane, Bidwell; Ayew, Cullen (Routledge 69mins), Lowe. Unused: Hamer, Bennett, Manning, Smith, Whittaker, Dhanda, Latibeaudiere, Roberts. Yellow cards: Ayew. Goals: Ayew 38.