With three games left to play of the regular season, the hosts are fourth in the Eastern Conference, while the visitors are down in sixth place.
Match preview
At this late stage of the campaign, Philadelphia do not have a great deal to play for, given that they are 14 points behind top-of-the-table FC Cincinnati, and they have booked their place in the playoffs, but they will still be looking to finish the season strongly.
The Union are now on a six-game unbeaten streak, but they have drawn on far too many occasions, with the spoils being shared in each of their last five games, most recently playing out a 1-1 draw against Columbus Crew.
In their trip to Lower.com Field, Jim Curtin's side were leading until the 72nd minute, courtesy of Nathan Harriel's first goal of the MLS season, but they were once again unable to hold on to the three points, with Cucho equalising from the spot.
Philadelphia Union have a solid home record against their upcoming opponents, winning three and drawing one of the last four matches between the two sides at Subaru Park, but they came unstuck in the reverse fixture earlier this season.
Indeed, Atlanta United ran out 2-0 winners back in July, with Thiago Almada and Brooks Lennon getting on the scoresheet, and the former heads into this Wednesday's game in good form, having scored in the last match.
Atlanta go into the match off the back of a 4-1 victory against CF Montreal, continuing their solid end to the MLS season, having lost just one of their last seven games.
As such, the Five Stripes are now up to sixth place, guaranteed to finish inside the top seven, and they would leapfrog their opponents in the table with a victory on Wednesday, as they are currently sitting two points below them.
Gonzalo Pineda's side are a real threat on the front foot, given that they have scored 61 MLS goals this term, the third-highest amount of any side in either Conference, and their away form has really picked up towards the back end of the season.
Atlanta United have lost just one of their last five away games, which should give them confidence heading into the upcoming fixture, despite their poor record at Subaru Park.
Philadelphia Union Major League Soccer form:
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Atlanta United Major League Soccer form:
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Team News
Philadelphia Union will be without midfielder Leon Flach, who has missed the last six games with injury, while Jakob Glesnes and Jose Martinez will also miss out, having been ruled out of the last three.
Chris Donovan was given the nod at striker in the last match, but the 23-year-old, who is not a regular starter, was withdrawn at half-time, and Mikael Uhre could be in line to come back into the team.
Atlanta United's only absentee is midfielder Osvaldo Alonso, with the Cuban missing the last six games due to injury, but Pineda otherwise has a fully-fit squad to choose from.
After the resounding 4-1 victory last time out, the Five Stripes are unlikely to make too many changes, but Edwin Mosquera may be rewarded with a start ahead of Saba Lobjanidze, having scored after being brought on as a substitute against CF Montreal.
Philadelphia Union possible starting lineup:
Blake; Harriel, Elliott, Lowe; Mbaizo, Bedova, Bueno, McGlynn, Wagner; Sullivan, Donovan
Atlanta United possible starting lineup:
Guzan; Lennon, Robinson, Abram, Wiley; Muyumba, Rossetto; Lobjanidze, Almada, Silva; Giakoumakis
We say: Philadelphia Union 1-1 Atlanta United
Philadelphia Union have drawn their last five MLS games, and the spoils have been shared in each of Atlanta United's last two away matches.
Given that the two sides are separated by just two points in the table, they are clearly evenly-matched, and we expect a draw this Wednesday.
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