Philadelphia Union boss Ryan Richter is excited to see his players test themselves against an "all-time" great in Robert Lewandowski, as they put their club-record unbeaten run on the line against the Chicago Fire.

The Union have enjoyed a meteoric rise up the Eastern Conference ahead of their midweek trip to Soldier Field, having gone unbeaten in 13 games since the World Cup break.

They have registered 11 wins in that time, the latest of which came by a 2-1 scoreline against Real Salt Lake on Saturday, with Bruno Damiani and Milan Iloski scoring.

The Union are sixth in the East with six regular-season games to play, three places and six points below Chicago, who themselves are just a point behind second-placed Inter Miami after beating New York City 2-1 last time out.

When asked if his side had enjoyed something of a kind of run in recent months, ahead of a big test against a direct rival, Richter said: "If we don't take points from those teams, then they'd be higher in the table.

"So that's also part of the reason why we're positioned where we are, and some of the teams we've played against, the reason we've been able to jump them is because we've had these head-to-head matchups.

"It's not like we've been playing against bad teams. Chicago is going to be a real test and it's one we have to be up for."

Chicago boss Gregg Berhalter can call upon former Bayern Munich and Barcelona striker Lewandowski, and Richter is relishing the task of going up against him.

"Yeah, it's another chance for us to play against a world-class player. And that's a pretty good opportunity for our centre-backs in particular," he said.

"But for our team as a whole, it's a guy that has the quality and the level where he can win a game with one touch at any time.

"So for us, we have to make sure that we're always aware of where were at. Don't give him space to operate. 

"He's one of the best strikers of all-time and we have to make sure we do a really good job with him."

PLAYERS TO WATCH

Chicago Fire – Robert Lewandowski 

Lewandowski has scored five goals in 13 appearances in MLS, with his time on the pitch only adding up to 300 minutes.

He has overperformed his expected goals (xG) figures of 3.79, while hitting the target with 10 of his 27 shots thus far, posting a conversion rate of 18.52%.

Philadelphia Union – Cavan Sullivan

Having made history as the United States' youngest-ever goalscorer during the international break, Sullivan laid on an assist during Philadelphia's victory over Real Salt Lake.

With that strike, Sullivan equalled the single-season record for MLS goal contributions by a teenager (20), surpassing Alphonso Davies (19 for the Vancouver Whitecaps in 2018) and going level with Diego Fagundez (20 for the New England Revolution in 2013).

MATCH PREDICTION: DRAW

The Philadelphia Union's 35 points won since the World Cup break are the most any team has collected in a span of 13 matches within a single MLS season in the post-shootout era (since 2000).

But they face a difficult task on Wednesday, against a Chicago side that have won nine of their 14 home games in MLS this year (D1 L4).

The Fire have also won three of their last six matches in MLS play (D1 L2), while they also won the last meeting between the sides, triumphing 2-1 at Subaru Park in March.

Given the Union's recent form, they will back themselves to leave Soldier Field with at least a point, in a game that could be a dress rehearsal for the playoffs.

OPTA WIN PROBABILITY

Chicago Fire – 43.2%

Philadelphia Union – 30.1% 

Draw – 26.7%