UPPER MONTCLAIR, N.J. – The New York Red Bulls may once again have to find a way to win without Rafa Márquez.

The Red Bulls Designated Player’s status for the decisive leg of the Eastern Conference Semifinal series against D.C. United on Wednesday is up in the air (8 pm ET, NBCSN, live chat on MLSsoccer.com) as the calf injury he sustained late in the first half of Saturday’s 1-1 draw has put him in jeopardy. Márquez said after the tie at RFK Stadium that he would be ready to go in the second leg, but head coach Hans Backe did not offer the same statement after Monday’s training session.

“I haven’t checked with the trainers today and it probably has to be a late decision,” Backe told reporters of Márquez’s availability. “I don’t think it’s a big one but we have to wait until tomorrow afternoon, evening until we know.”

Backe added that Márquez will undergo an MRI on Monday, a strange development considering the Mexican international was pulled at halftime on Saturday as a precaution to calf tightness.

The Red Bulls boss also touched on the much-discussed halftime argument he had with Márquez, but he said the player was just upset with having picked up another injury in a season littered with them.

“He was very frustrated with the calf,” said Backe. “He has been picking up that calf a number of times this season and going into the playoffs, he played very well. Picking up late in the first half, he was just upset over that.”

Another topic Backe discussed was Márquez stating after Saturday’s wild draw that the Red Bulls needed a change in attitude if they are to make a run in the playoffs, and the head coach seemed to agree with his center back’s assessment.

“When you go into playoffs, they are different games,” said Backe when asked about Márquez’s comments. “It changes. It becomes a different game if you talk about the defending, the pressing game, tackles, and things like that.

“Everyone has to be ready to do the dirty work for 90 minutes and after this game, everyone should be aware of it, the price you have to pay to win the whole way.”

Franco Panizo covers the New York Red Bulls for MLSsoccer.com. He can be reached at Franco8813@gmail.com.