Meanwhile, the visitors make the trip to Oakwell on the back of nine matches without defeat, keeping the Lions in the race for the top six.
Having started the season as candidates to avoid relegation, many people had been expecting Barnsley to settle for a spot in mid-table during the second half of the campaign.
However, Valerien Ismael's side are now regarded as one of the best teams in the division, the Frenchman having recently guided the Tykes to four victories in a row.
The latest success, a 2-0 win at home to Stoke City, has helped put some distance ahead of 11th position, but complete focus will be on trying to end an increasing improving campaign with the most unlikely of promotions.
While goals have not been Barnsley's strong point, seven strikes in five matches have still led to 13 points, highlighting the defensive rearguard at the other end.
Much of the attention ahead of this match will be on Barnsley, but the recent progress of Millwall is something which should not be ignored.
Having previously been on the brink of the sack, Gary Rowett has helped the Lions put together a nine-match unbeaten record since January 20.
Still sitting six points adrift of the playoffs, Millwall are no more than outsiders in the race for promotion, a consequence of only achieving draws against Wycombe Wanderers and Luton Town.
Nevertheless, Rowett will be proud of the club's recent resurgence, arguably proving that he remains the right man at the helm in the long term.
Seven of Millwall's last eight goals in the Championship have been scored in the final quarter, including their last-gasp equaliser at Kenilworth Road.
Barnsley Championship form: DDWWWW
Barnsley form (all competitions): DLWWWW
Millwall Championship form: DWWWDD
While Jake Cooper does not require surgery on a shoulder injury, the centre-back will remain out of the side for this game.
Barnsley possible starting lineup:
Collins; Sollbauer, Helik, Andersen; Brittain, Palmer, Mowatt, Styles; Chaplin, Dike, Morris
Millwall possible starting lineup:
Bialkowski; Hutchinson, Pearce, Evans; Romeo, Woods, Thompson, Malone; Wallace, Smith, Bennett
We say: Barnsley 2-1 Millwall
With both teams putting together their best form of the season, we expect a fiercely-competitive encounter in Yorkshire. However, sensing an opportunity to break into the playoffs, the home side could show the extra ambition required to collect all three points.