Both sides have performed significantly above expectations so far this season, with Frankfurt in pole position to qualify for the Champions League for the first time in the club's history.
Adi Hutter's side held onto fourth place last weekend after earning a creditable 1-1 draw at second-placed RB Leipzig.
Less than a minute into the second half, the Netherlands international fizzed an effort from range, with Trapp unable to divert the ball away from danger as Emil Forsberg pounced on the rebound to break the deadlock.
However, Hutter's side demonstrated the spirit and quality which has helped them become unexpected Champions League qualification contenders, with Amin Younes and Daichi Kamada probing between the lines.
The Japan international levelled the proceedings by cleverly diverting Andre Silva's past a helpless Peter Gulacsi, with both sides unable to find a winner in a surprisingly frantic finale to the match.
While Hutter would have been more than satisfied with avoiding defeat at Leipzig, he may be mildly concerned that his side have failed to win their last three matches, with Borussia Dortmund closing the gap behind them to only two points.
Frankfurt must get back to winning ways if they are to ensure they remain in the top four at the end of the weekend.
Still only in their second ever Bundesliga campaign, few would have tipped Union Berlin to be challenging for a European qualification spot this late into the season.
However, a five-game unbeaten run has seen them climb back into seventh spot, only six points behind Frankfurt.
As such, an unthinkable Champions League qualification spot is still not completely out of reach, particularly if they can upset Frankfurt on their own ground on Saturday.
Urs Fischer's side came from behind to win at home for the first time this season against FC Koln last weekend, with Ondrej Duda's penalty giving the visitors the lead at the half-time interval after Jonas Hector had been tripped inside the area.
While that was Duda's first penalty of his career, one man who is no stranger to the penalty spot is Max Kruse. The midfielder converted his 19th Bundesliga penalty three minutes into the second half, taking his success ratio from the spot to an astonishing 95%, with Christopher Trimmel completing the turnaround by smashing the ball into the far corner from the back post.
A win at Frankfurt on Saturday could see Union Berlin move above Bayer Leverkusen into sixth place, which with only eight games of the season remaining would be an even more remarkable feat by Fischer and his players.
Frankfurt will be without Amin Younes and Tuta through suspension after the pair both picked up their fifth cautions of the season against Leipzig.
Kamada shook off a knock to feature and score against Leipzig but was substituted late on and may not be risked this weekend, with Eric Durm, Martin Hinteregger and Almamy Toure all ruled out, leaving Hutter with plenty of holes to fix in his side.
Christopher Lenz and Liverpool loanee Taiwo Awoniyi have missed out with muscle injuries in recent weeks, and it remains to be seen whether they will return in time to feature from the bench or be saved until after the upcoming international break.
Eintracht Frankfurt possible starting lineup:
Trapp; Ache, Ilsanker, N'Dicka; Barkok, Sow, Hasebe, Rode, Kostic; Silva, Jovic
Union Berlin possible starting lineup:
Luthe; Friedrich, Knoche, Schlotterbeck; Trimmel, Promel, Andrich, Endo, Ingvartsen; Kruse, Musa
We say: Eintracht Frankfurt 1-1 Union Berlin
With Frankfurt missing several first-team players, we can see Union Berlin gaining a positive result from the match to extend their unbeaten run. These two sides have both drawn the most amount of games (11) in the division this season, too, so it would be no surprise to see another share of the spoils.
Indeed, Frankfurt appear to have run out of steam a little in recent weeks and could lack creativity without Kamada and Younes, although the combination of Silva and Filip Kostic can still hurt any side.