HARRISON, N.J. – Although Tuesday’s press conference may have marked the official presentation of new Red Bulls Designated Player Rafael Márquez, the Mexican National Team captain had already participated in his first practice session earlier that day.

RBNY manager Hans Backe was immediately struck by how the addition of another world-class player changed the regular course of training.

“It’s rather interesting,” Backe said. “The reaction of the other players when he was in was 10 to 15 percent better quality from every player – focused on every pass, the movements. It was a bit ridiculous to see how one player can change the quality of one session.”

Both player and coach indicated that it is a real possibility that Márquez will make his debut on Sunday in a nationally televised match against the Chicago Fire at Toyota Park (9 p.m. ET, ESPN2 and ESPN Deportes).

Although Márquez indicated that he was working out on his own before today, he is coming off a three-and-a-half-week layoff following the World Cup. Wednesday represented his first real practice session since Mexico were eliminated in South Africa.

“I want to play as soon as possible,” Márquez said. “If there’s a chance to play against Chicago, I will.”

Backe said it's realistic that Márquez could play a half against the Fire, in a match that could see him go up against fellow DP and Mexican international Nery Castillo.

The manager added that he thought it will be a couple of weeks before Márquez is at full fitness.

“Those high profile players have a lot of commercials, events, finding apartments,” Backe said. “But they are quality players and that’s why I think they don’t need that much time to settle in.”

It has been made clear that Márquez will play in central midfield in Chicago, a position which he says he prefers over central defense.

With two games in hand, the new-look Fire could still provide RBNY with fierce competition in the race for the postseason.

Whether the Red Bulls are in the race for the Eastern Conference crown or scrapping for a playoff berth will likely be determined in the next two weeks, when RBNY face their toughest stretch of the remainder of 2010.

Backe’s side is looking at four league games in a span of 13 days, with a FIFA match date for their international players squeezed in for good measure.

“We will be shorthanded probably with five players against Toronto [Aug. 11] and we will have exhausted players against the Galaxy [Aug. 14] with players coming from Paraguay and Estonia,” Backe said. “I’m a little frustrated by that. I don’t see how that can be fair.”