What we know and what we don't: Philadelphia Union

Is it a six-pointer? Technically, no: the New York Red Bulls and Philadelphia Union can finish this game no further than four points apart.

Nonetheless, it is a match of great significance that neither team wants to lose and both would prefer to win, since it may determine which of them spends the next week sweating anxiously below the red line. The Union has won three in a row - its best run of the year so far - and is still somehow sweating in sixth in the East. RBNY is the only team in the top six of the Eastern Conference that hasn't managed to put together a winning streak of more than two consecutive games to date.

Neither team has to win, but that will be scant consolation for whichever one doesn't should there be a winner in this game.

Here's what we know:

• Philly is good at home; the Red Bulls aren't good on the road

The Union has won its last four home games in MLS, and hasn't lost a league match at PPL Park since May 17, when the Revs won 5-3.

The Red Bulls haven't won a road game, in any competition, since June 8 - when they beat the Revolution in New England, 2-0.

The form book's prediction is pretty clear.

• RBNY isn't very good at immigration

Tim Cahill played a game for Australia in London last Monday, and was back with RBNY in time for Wednesday's match against D.C. United. Ambroise Oyongo played a game for Cameroon in Cameroon on Wednesday and by Friday was...still in Cameroon.

"Before practice began, he was at the embassy in Cameroon, finally finishing up his paperwork and going to get in a plane," said Mike Petke after training on Friday.

Huh?

If Oyongo was catching a commercial flight, he was looking at something like a 17-hour journey via Europe to get back to the US. Which means he'd be arriving in the US sometime on Saturday morning, at the earliest. Even if he flew back on a private jet (one imagines Red Bull GmbH has a few of those at its disposal), it's a long flight. Cameroon is close to 6,000 miles away from the USA, or more than twice the distance between LA and New York.

He's young and fit, so it's not entirely insane to suggest he can hop off a long-haul flight and suit up to play left back against (if Philly chooses to let them play) one of the best right-flank pairings in MLS (Sebastien Le Toux and Sheanon Williams). But it doesn't seem ideal preparation.

The Red Bulls knew Roy Miller would likely be missing for this game (he's penciled in for the Copa Centroamericana final). Oyongo's call up by Cameroon was unexpected, and the fact he needed to get some paperwork processed at the US embassy in his home country suggests there were some immigration hurdles to clear for him to leave the US mid-season. Hurdles that presumably could not be cleared before he left.

Whatever the issue, it seems unreasonable to expect a 23-year-old soccer player to deal with it. Evidently, RBNY couldn't figure out a solution that put Oyongo back with his team in appropriate time to join the preparations for playing Philadelphia.

The club doesn't make immigration law, so it is not at fault for whatever complexities tied up Oyongo's return. But this isn't the first time the team has stumbled when asked to manage a player's visa requirements. When Luke Rodgers was prevented from returning to RBNY in 2011, it appeared to be an unfortunate but isolated incident.

However, to paraphrase Oscar Wilde, to lose (albeit temporarily this time) a second player to a visa snafu looks like carelessness.

• Both teams have one eye on CCL

For the Union, this match is the prelude to its best shot at winning a major trophy this season: the US Open Cup final. That game will be played in Philadelphia on Tuesday. If it is won, Philly will be the first team to qualify for the 2015-16 CONCACAF Champions League.

RBNY plays Montreal Impact on Wednesday, in a CCL 2014-15 group stage match that will determine just how hard it will be for the Red Bulls to qualify for next year's knockout phase.

So both clubs have to consider the implications of going all out to win a league game with important implications for their MLS playoff hopes against whatever priority they give to the regional competition. The match-day squads may reflect the fact both coaches have some incentive to try to keep a little strength in reserve for the upcoming midweek matches.

Here's what we don't know:

• Who is the least bad option for Mike Petke at left back?

As outlined above, the most obvious replacement for the absent Roy Miller on the left side of defense, Ambroise Oyongo, may not be available - and probably ought not to be considered for selection, given the length of the journey he will have made just to get back to the club.

Bobby Convey is still rehabbing his septum. Connor Lade would appear to be on the outs with RBNY.

Mike Petke's only options at left back for the game in Philly look like one of his out-of-favor right backs - Kosuke Kimura or Richard Eckersley - or whichever center back (Armando, Ibrahim Sekagya, Damien Perrinelle, or maybe even Matt Miazga) seems least likely to struggle with the assignment.

Long shot options include Ian Christianson (who is left-footed) or the ever-willing, not-always-capable Eric Alexander.

We don't know who Petke will select to play the position, but if he sticks with a formation that requires a left back, we know his options are either the untested or those who have been tested and found wanting.

• Is it Cahill time again?

Last year, when the Red Bulls won six of their last eight games - and tied the other two matches - en route to the Supporters' Shield, Tim Cahill was essential to keeping the team's unlikely charge going. He scored four goals during that epic run-in, all of which were important: the match-winner against DC United to start things off; the equalizers against Seattle and New England; and, perhaps most importantly, the magnificent opening goal on the road in Houston which seemed to give the team the confidence it needed to kick on and win its last two games of the year.

This season, he has been mostly playing in midfield and mostly absent from the score sheet.

Now, with RBNY in need of points and Bradley Wright-Phillips quite possibly unavailable to score the goals required to get them, the stage is set for Cahill to remind us all of his value to the team.

• Can Maurice Edu make it three out three?

Edu has an unusual streak going against the Red Bulls this season: he's won penalties in both matches played against them this year.

Back in April, he caught the RBNY back line panicking and saw a goal-bound shot blocked by Ibrahim Sekagya's arm: handball, red card, penalty for the Union. And in July, he schooled Eric Alexander in the art of set-piece jostling: a little tug on Alexander lured the RBNY midfielder into a compensatory action, which Edu would seem to have been waiting for - he hit the deck with ostentatious enthusiasm, drawing the referee's attention and the penalty call.

The Red Bulls would do well to avoid conceding a third consecutive penalty to the Union, and perhaps the best way to do that is to keep Edu out of the penalty area.