David Wagner's side have dropped into 10th position due to their recent struggles, but Union Berlin have problems of their own, currently occupying 14th spot in the table as they battle to remain clear of the relegation zone.
Nine wins, four draws and 16 defeats - that is how Union Berlin have performed in the Bundesliga this season; a total of 31 points has left them in 14th spot, only three points clear of 15th-placed Mainz.
The gap from the capital side to Fortuna Dusseldorf in 16th is only four points, meanwhile, which is an indication of their precarious position in the table heading into the final straight.
Die Eisernen are competing in their first ever season at this level of football, and they can be largely proud of their performances in the Bundesliga during the 2019-20 campaign.
The club's supporters are likely to be fearful of what might be ahead, though, as they have lost four of their last five in the league, including heavy defeats in their last two away matches.
Union Berlin will enter Sunday's match off the back of a 4-1 loss at Borussia Monchengladbach last weekend, while the capital side have not actually triumphed in the league since the end of February.
Schalke, meanwhile, have also been in disappointing form since returning to action in the middle of May. Indeed, Wagner's side suffered a 4-0 defeat to Borussia Dortmund in their first game back before Augsburg recorded a 3-0 victory over the Royal Blues on May 24.
Die Knappen have also lost their last two in Germany's top flight against Fortuna Dusseldorf and Werder Bremen to slide down the table, with the team now occupying 10th position.
Schalke are still in the argument for a top-six finish as they sit just five points behind Wolfsburg in the final Europa League position, although the club's supporters will not be too confident considering what they have seen from their side over the last couple of weeks or so.
Wagner's team have just not been able to get to grips with the behind-closed-doors fixtures, but they did record a 2-0 victory against Union Berlin in the reverse match earlier this season.
Union Berlin Bundesliga form: DLLLDL
Union Berlin form (all competitions): LLLLDL
Schalke Bundesliga form: LDLLLL
Schalke form (all competitions): LDLLLL
Union Berlin possible starting lineup:
Gikiewicz; Friedrich, Schlotterbeck, Subotic; Trimmel, Gentner, Andrich, Lenz; Ingvartsen, Bulter; Andersson
Schalke possible starting lineup:
Nubel; Kabak, Sane, Nastasic; Kenny, Boujellab, Schopf, Oczipka; Caligiuri, Burgstaller, Raman
We say: Union Berlin 1-1 Schalke 04
Both sides are likely to have earmarked this fixture as a good chance to put three points on the board, but neither will enter the contest in good form. Schalke's losing run is going to end at some point, and we expect the visitors to pick up something for their efforts on Sunday afternoon.