Members of the International Olympic Committee's evaluation team landed in Chicago to look over the city and determine if it is worthy of hosting the 2016 Olympic Games.
Chicago's chances of landing the 2016 Olympic Games may be as high as 50 percent amid talk that the steam has run out of Madrid's bid and a possible poor showing by Tokyo in June.
It's believed that dozens of International Olympic Committee members are still undecided, but many Olympic experts say they believe the current contest is between Chicago and Rio de Janeiro.
"The fact that there are lots of undecideds means that we are winning people away from where they thought they were going to vote," said Chicago 2016 Chief Patrick Ryan.
Fueling the fire against Spain: an editorial in that nation's sports daily newspaper which "issued an early death certificate on the candidacy," the German news agency DPA recently reported.
And while Madrid's number two, Antonio Ferdandez Arimany, doesn't necessarily agree, he acknowledges that the competition is fierce.
"It is true that Rio has gone away strengthened after the presentation in Lausanne," he said. "Rio made a great presentation there, from what we have been told."
Rio's presentation included a reminder that South America is the only continent -- aside from Antarctica -- to never host the Olympic Games.
"Can you imagine the possibility for a continent which has never had the chance to organize an Olympics, and how much that can motivate people?" Brazilian President Luiz Inacio Lula da Silva said in June.
Even the top daily in Spain, marca agreed, calling Rio's bid the "most favorite" among the four, while Madrid was dubbed "the least favorite with Tokyo."
The United States Olympic Committe's Bob Ctvrtlik agrees, and said he likes "where we are," but cautioned that experience shows the bid process is a contest which can be won or lost on the very last day.
"As we've been counseled by almost every (IOC) member we meet with, work until the last hour of the last minute because you just never know," Ctvrtlik said. "The final presentation is very important on those swing votes. That's where we'll try to make our final presentation much more emotional, as opposed to technical."
Ryan said the front-runners can change depending on whom you ask.
"If you talk to 20 different people, or 21 different people, you might get seven who say 'Rio and Chicago,'" Ryan said. "The next seven say, 'No, no... Madrid and Chicago,' and the third say, 'Tokyo and Chicago.' As long as they say, '...and Chicago,' we're happy."
The announcement on the 2016 host city will be made by the IOC during a ceremony in Copenhagen, Denmark on Oct. 2.
Full Coverage: Chicago's 2016 Olympic Bid