I watched tomorrow night's "Chuck" season finale yesterday, after news of the show's fifth season renewal came in. And without spoiling anything about what happens, the end credits rolled and I said to myself, "Thank God NBC renewed it, because I cannot wait to see what they do after this one."

Chris Fedak, the show's co-creator, was feeling a similar excitement for the possibilities of a fifth season as he worked on the finale, even though he believed the odds were, at best, 50-50 for renewal due to the show's recent ratings dip.

I spoke with Fedak a few minutes ago, for an interview I'm going to present in two parts over two days. After the jump is Chris' reaction to the renewal, the knowledge that next season will be the final one for "Chuck," and the challenges that have come the last two seasons as NBC has ordered more episodes partway through the year. Tomorrow night, after the finale, I'm going to post both my review of the episode and Fedak's explanation for some of the things that happen in it.

When did you know you were coming back?

It's been a day by day situation. We didn't know until the rumors started getting out there that we had a chance. It's really been the last couple of days that we knew.

So how were you feeling over these last few weeks, especially given how the ratings dropped late in the season?

There's always a number of different feelings. One is you look at a number that's lower than you want. The brass tacks of television is that you need a number you can feel good at. But we also had our core viewers and some things going in our direction We all wish the numbers were different by the end of the season, but we knew we had some big exciting stories and we had an exciting finale coming up. We had some things in our back pocket we felt good about.

But if I were to have injected you with truth serum a week ago, what would you have set the odds for renewal at?

I would have said 50/50.

You got the renewal for a fifth season, but it's also the final season. How does that feel?

We're excited. We're stoked to be able to tell more "Chuck" stories. It's a unique and in some ways precious show. We've managed to survive 5 years. Josh (Schwartz) and I love telling these stories, along with the rest of the writing staff. For us, it's the ability to tell 13 more stories and close out the story in a super fantastic way. And to know what we're doing, that that's the gameplan all along? It's great. That's something you don't usually have when working on a network television show. On our show, we've had finales built into our episode 13, but we'll be able to design the season in a very specific way.

Has NBC suggested there's any possibility of getting the order extended the way it has these last two seasons?

We've learned to say never say never again - that's a James Bond reference - but the gameplan is to focus on these 13 and to build towards an ending in the 13th.

While I'm sure you were happy in seasons 3 and 4 to get more episodes to work on, how big of a challenge is it to have to construct your seasons in that unpredictable way?

It is a real challenge from a storytelling perspective. Naturally, you won't find a screenwriting manual or guidebook that tells you to have an epic finale midway through your season. That's not a usual move. It's tough, from a structuring a story perspective. But for me, it's always been an opportunity. When we got 6 more episodes in season 3, those 6 episodes gave us an opportunity to explore things in the show you just wouldn't do in a shorter season. Hard to imagine season 3 without the "Honeymooners" episode. And with these extra 11 we got in season 4, it's hard to imagine season 4 without bringing Timothy (Dalton) back and exploring Volkoff. The challenges are outweighed by the way you're able to take a character and explore them in a greater way. We've now seen a little more of the Roan (Montgomery) and Diane (Beckman) relationship, for instance. That's the fun thing we get to do. But it's certainly a challenge from a storytelling standpoint. And doing 11 more is a lot different from doing 6 more.

Yeah, this year you had to build a whole second arc, where with the 6 last year you could basically just do 6 episodes of "Chuck" with a climax at the end.

With the 11-episode order, we had to reboot the season in a major way. Launch new storylines, set up new characters. It's challenging, but to be able to work on the Chuck show, considering how unique it is, it's a wonderful thing to be able to do.

Without giving anything away, what can you tell your fans about the finale tomorrow night?

Our finale, in the tradition of all "Chuck" finales, is everything and the kitchen sink. I hope that everybody enjoys it. It's got some epic emotional stuff as well as some great action. It's another epic "Chuck" finale. I couldn't be more proud of it. We have a great time making the show, and you can see that through what comes on screen. I hope people really like it.

Alan Sepinwall may be reached at sepinwall@hitfix.com