Here's my reasoning.
Senators 2, Lightning 3
Unlike the basement-dwelling Islanders, who the Sens beat last week, the Lightning are much improved when compared to last season. Though they had a few days to lick their wounds after the loss to Pittsburgh, I expect the Sens will still be tired. The Senators still haven't found their scoring touch, but Tampa's big guns are on fire lately, it adds up to another hard-fought loss for Ottawa.
I guess we'll see the outcome during tonight's game. But you can bet that if the Sens lose, and I win, Mendes will never hear the end of it. (His email is pretty easy to guess.)