Following a 2-1 win over the Chicago Fire on Saturday to restart MLS play, the first-place Colorado Rapids will travel to Southern California to take on the Los Angeles Galaxy. Here are some things to consider:

What will Colorado’s back line look like?

The Rapids will be without three defenders (Bobby Burling, Marc Burch, Mekeil Williams) for their midweek game against the Galaxy, and newly-recalled Dennis Castillo could be called upon to fill in for any one of them.

Where Castillo will be inserted on the field is unknown, but it will give us a chance to see how he adapts (if he plays) to Pablo Mastroeni’s revamped high-tempo brand of soccer. He last saw MLS time for the Rapids in their 3-1 win over Seattle on April 23, when he assisted on Kevin Doyle’s goal in the 86th minute. He had a taste last Wednesday in a U.S. Open Cup win over Colorado Springs Switchbacks.

Bobby Burling is out with a right knee injury and Marc Burch is suspended on yellow card accumulation. Marlon Hairston stepped up in a big way against Chicago, though, creating four chances and recording two shots on target in just his third start of 2016.

The Galaxy lead the league with 27 goals, and Giovanni dos Santos has been on fire lately, scoring in five of his last eight starts. It’ll be interesting to see how Mastroeni positions his defense.

Who wants it more? 

Los Angeles has won their last seven home games. Colorado has gone unbeaten in their last 10 games overall, and have not lost away from Dick’s Sporting Goods Park since April 9 of this year at Real Salt Lake. The last time Los Angeles lost to the Rapids at home was September 7, 2013.

With FC Dallas’ 2-0 loss to Sporting Kansas City on Sunday, the Rapids maintain their three-point lead at the top of the Western Conference table, and will be looking for a bigger cushion on Wednesday.

The last time these two clubs met, Marco Pappa stole three points from the Galaxy with a 95th minute goal to give the Rapids the 1-0 win in home opener. Speaking of Marco…

Will Marco be Marco?

Pappa is back after sitting out almost two months with a sprained MCL in his left leg. He came on Saturday in the 83rd minute and scored six minutes later to put Colorado in sole possession of first place in both the West and the league.

Mastroeni said after the Rapids’ win Saturday that Pappa’s fitness is getting better. He also wanted to give his midfielder some minutes, but not push him to where he would land back on the MLS Injury Report.

Pappa has scored twice this year and has three assists and two game-winning goals. He’s a leader on the pitch and on the bench, and certainly gives this club a boost when they need it.

Conclusion

This will be a hard fought matchup from both sides, and Bruce Arena’s Galaxy will certainly look to take advantage of the Rapids’ depleted back line. The Galaxy still remember Pappa’s winner on March 12, and Colorado better be ready for some attempted payback.