Roger could've easily lost that match against Ivo in Basel last year if it wasn't for the local crowd helping him a bit. Totally depends on how well Ivo serves, I guess. So it's indeed on Ivo's racquet.
Federer usually rises to the Karlovic challenge and likes to show off his return. I think this match would require some back issues out of Fed for him to lose. Ivo will be happy with having set the ace record, 180 ranking points, and $100,000+. Good week but it ends here I'm afraid.
this guys usually play tiebreakers. But Fed is more effective in just reacting to a serve and resetting the point instead of making something out of a return. Fed can return good flat serves but hates somewhat heavy kick serves. i say fed in 3 set tie breaks
Ivo was so close in Basel this match will be similar, fast surface, crowd 100% behind Roger, but i think Ivo has good chance again, when serving great his match vs Roger is like 60:40 for Roger i like his chances here and would be amazing if he can upset Roger in Halle