First off, nobody is out to get you. So don't worry about that. I've had this problem in the past as well. The key here is honesty and knowing shit.
1) Honesty
If you don't know about it, don't bullshit. Be upfront about it. You're going to look worse if you start to try and answer questions or stay in conversation. Instead say, "I don't watch too much football actually, I usually do (insert something interesting here)". Now you can start to talk about that! Say it with confidence though. Don't say, "Oh I don't know about that computer stuff, but I wish I did". Instead say, "well I actually specialize in this area, but that stuff is really cool too. I focus more on (insert this area)."
2)Knowing Shit
Read newspapers, magazines, books, talk to as many people as you can. Start to learn the ins and outs about ALL topics. Then you can start to gear the conversation to where YOU want it to go. All of a sudden look who can't keep up.

Life isn't all about sports. It's about EVERYTHING. So know stuff and try and bring it up ASAP so you can start talking about the things YOU want. This also seems to be a lack of confidence issue. You might be letting the other person take over and let them lead the conversation. Well, today, it's a new you. You will start to lead the conversation and if it doesn't go where you want. Direct it somewhere else.
Hope that helps!
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