Mats Hummels accepts it will be "difficult" for Borussia Dortmund to secure a top-four finish after losing 2-1 at home to Eintracht Frankfurt.
Andre Silva grabbed the winner in the 87th minute at Signal Iduna Park, pushing fourth-placed Frankfurt further clear of their hosts in the battle to qualify for next season's Champions League.
Dortmund sit fifth in the table but are seven points adrift. They have won just once in four Bundesliga outings and have now reached double figures for defeats in the competition this season.
With just seven games remaining, Hummels fears BVB have left themselves with too much to do during the run-in.
The centre-back - who scored just before half-time to cancel out an early own goal by team-mate Nico Schulz - felt the hosts paid the price for not taking their chances before losing control of the game.
"On the one hand, we clearly have to hold our hands up for our chance conversion. We had so many opportunities, especially situations that should be 100 per-cent chances," Hummels told Sky Sports in Germany after Dortmund had managed to get just five of their 19 attempts on target.
"In the second half, we never managed to get into central positions in front of goal or create a good situation. We also allowed the game to get really out of control.
"In that regard, there were parallels to the Cologne game [which ended in a 2-2 prior to the international break]. We were not precise, focused or just technically good enough on the ball. We obviously should have also made better use of the chances that we had.
"We now need to ensure that we pick up wins. Unfortunately, we've dug ourselves another big hole with our most recent games. Even with six or seven wins, it's going to be difficult to get fourth place.
"We need to put in the performances in the Bundesliga and then see where that gets us. In the cup competitions, we want to try to make it through."
You deserve better, we need to be better. pic.twitter.com/9jTPFiyy3Z— Jude Bellingham (@BellinghamJude) April 3, 2021
Dortmund - who had won nine on the spin at home against Frankfurt prior to Saturday's meeting - face Manchester City next in the first leg of the Champions League quarter-final tie.
The possibility of missing out on appearing in the competition again next season will raise questions over the club's ability to hang on to their prized asset in Erling Haaland, who has been linked with a host of Europe's leading clubs.
Mino Raiola - the striker's agent - was in Spain this week to hold talks with Barcelona and Real Madrid, while he was reportedly set to do the same with a select number of Premier League teams on Friday, too.
However, Dortmund director Sebastian Kehl has made clear there is no cause for panic within the club, despite the consistent rumours surrounding Haaland's future.
"Our position is clear: we are planning with Erling," Kehl told Sky. "We are very relaxed about the situation."
City are one of those teams rumoured to be interested in Haaland - who has scored 10 goals in six Champions League games this campaign - but Pep Guardiola dismissed the possibility of signing the 20-year-old ahead of going up against him in Europe."