Striker Nery Castillo and Barcelona defender Rafa Marquez are among the candidates for the Fire, who are attempting to add two DPs to replace Cuauhtemoc Blanco. But the Revolution will not have to change their game plan tonight against the Fire, since the introduction of the new player is scheduled between SuperLiga contests. Morelia and UNAM Pumas will meet in the second game.

The Los Angeles Galaxy are in contention for Milan’s Ronaldinho, but he would be coming with a high price tag and seems headed back to Brazil, where Flamengo has indicated it could deliver on a 5 million euro annual salary.

The Revolution are also working on signings, but will not likely go for a high-profile performer. The Revolution are planning to add at least one player who was on trial in Foxborough recently, according to a team source.

Last month, three trialists were announced by the Revolution: Abdou Fall and Ferdinand Gomis (both from Senegal) and Rhonald Moreno (Colombia).

“We’ve been pretty consistent in what we’ve said in terms of a designated player,’’ said Michael Burns, the Revolution’s vice president of player personnel. “Since the [DP] was established, we said he would have to do something on the competitive side and also on the other side, as well, as far as marketability, ticket sales, to be a draw in the Boston area.’’

Are the Revolution, who have never signed a DP, feeling pressured to match other MLS teams in the marquee player sweepstakes?

“I don’t look at it like that,’’ Burns said. “We are trying to bring in players, whether designated players or not. We want guys who will help the team, and we are not so caught up in does it have to be a DP or not.

“In the short history of the league, there has been no correlation between having a [DP] and that equaling a championship. Having said that, we want guys who will help the team.’’

The Revolution have negotiated with Portuguese stars Rui Costa, Luis Figo, and Pauleta, plus England’s Robbie Fowler as potential DPs in the past.

Chicago had one DP — Blanco, who sparked the Fire as a playmaker and drew attention from the area’s large Mexican population. Though Blanco, 37, continued in a starting role on the national team during the World Cup, he has dropped down to Mexico’s Liga de Ascenso with Vera Cruz.

Castillo signed last season with the Ukrainian club Shakhtar Donetsk, then was loaned to Dnipro Dnipropetrovsk. Castillo, 26, was born in San Luis Potosi, but also has Greek and Uruguayan heritage. Castillo, who began his European career with Manchester City in 2007, played for Mexico and has scored six goals in 23 international appearances, but was not chosen for the World Cup. Olympiakos and PAOK of Greece have been negotiating to sign Castillo.

The Revolution, who defeated Pumas, 1-0, in their SuperLiga opener Wednesday, are 6-0-0 against Mexican teams in three years of the competition . . . Steve Ralston (dislocated elbow) will not play for the Revolution tonight. Also out are Taylor Twellman (concussion), Zak Boggs (concussion), Preston Burpo (leg), Jason Griffiths (hamstring), and Edgaras Jankauskas (adductor). Calen Carr (quadriceps) is out for Chicago.

Frank Dell’Apa can be reached at f_dellapa@globe.com.