Facing their second game in four nights, the Philadelphia Union head to Dick’s Sporting Goods Park to take on the Colorado Rapids. Kickoff is scheduled for 9 PM EST (TV: Altitude, The Comcast Network, MLS LIVE).

When the schedule was announced, nobody would have thought that this Saturday’s match would be between the two first place teams in Major League Soccer. However, that is what we have in store for during Saturday night’s game.

Philadelphia comes into Colorado off the heels of a controversial 2-2 tie Wednesday to Orlando City. As of Friday night, the Union sit on 19 points through 12 games, which is two points better in one less game than second place, New York City FC. Additionally, the Blue and Gold are undefeated in their last six games.

Colorado has had a week's rest after defeating the Seattle Sounders 1-0 last Saturday. The Rapids have 27 points through 13 games, which is one point better in one less game than second place, FC Dallas. Colorado also sits on top of the early MLS Supporters’ Shield standings as well. One main contributor to their plentiful amount of points is their play at home. Colorado has not dropped a single point at Dick’s Sporting Goods Park, winning all six of their home matches this season.

With both teams looking to keep up their winning ways, let's look at some possible keys to this match.

Selection dilemma for Colorado

For Saturday’s match, Colorado will be without two of its most important players. Colorado midfielder Jermaine Jones and winger Shkelzen Gashi will both be away from the Rapids due to international duty. 

Manager Pablo Mastroeni might be able to replace Jones’ soccer skills but will struggle to replace the United States International’s leadership and toughness on the field. Jones plays in the number ten role for Mastroeni’s side and, with the 34-year-old preparing for the Copa America with the United States, Dillon Powers looks in line to get the start. Powers is no stranger to playing this season in the midfield as he started the first five games of the season for Colorado. He will need to be at his best in order to lead this Colorado side to a good result.

Former Union goalkeeper Zac MacMath to face former team

Zac MacMath was a part of the Philadelphia Union for his first four MLS seasons. The sides did not end on the best of terms as MacMath was sent to Colorado at the beginning of the 2015 season in spite of MacMath finally showing signs of living up to his potential at the end of the 2014 season.

On Saturday night, he will get the opportunity to take on his former squad. When playing a former team, emotions are sure to be high and, at a position such as goalkeeper, MacMath will need to keep his in check in order to help organize his defense. As in 2014, MacMath is showing signs of his potential and, if he can continue his good form, Colorado will certainly be in line for a good result.

How will Jim Curtin rotate his squad, if at all?

For Philadelphia, one key to watch is how Philadelphia Head Coach Jim Curtin will rotate his squad after his squad’s tie on Wednesday. To further add to the dilemma, Orlando’s Camping World Stadium is a turf field. Players that have been recently recovering from injuries or are older may have a difficult time playing a second time in four days. Look for players such as Tranquillo Barnetta as well as Brian Carroll to be rotated from the squad with players such as Roland Alberg looking to come in.

Keep with VAVEL USA for postgame coverage and analysis of Saturday’s game.