Japanese language help?

Question:

From a website I read,it said :

Ashita ame ga furu to omoimasu

"If the content of the quoted clause expresses one's intention or speculation about a future event or state, a volitional form of a verb is used preceding "~ to omou." To express a thought other than one's volition or opinion toward the future, a plain form of a verb or adjective is used preceding "~ to omou" as shown in the examples above."

Oyogi ni ikou to omou

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Okay now i have one question look at the sentence below:

Watashi wa kondo no sakka no shiai wa kitto burajiru(Brazil) ga katsu to omoimasu.

At the up coming soccer match,I think Brazil will win.

Now isn't the sentence above is a "speculation about a future event or state",so why isn't the VERB in Ikou form(volitional form)?

Answer:

Nope, it isn't supposed to rain tomorrow. And it's not volitional because I really would like something to break up this heat.