<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Andrew Webber:
Don't know about the United factor, but if you did that on an AC ticket with AC points, you supposedly have top priority over everyone trying to upgrade. But remember when you're talking to the agent, you're not "upgrading" since you've paid for a Business Class seat (and using the word "upgrade" may affect their response).
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It should not be a problem at all.