Well, Dumbstruck in Delaware, I should begin by saying that Mahabharatan is a damned fine coinage. For readers who don't know (and I'm sure there's one of you), the Mahabharata is a Sanskrit epic that's about ten times longer than the Iliad. I like mahabharatan. I shall steal it and use it for my own sinful purposes.
Can I do better? I'm not sure. It's pretty easy to coin words for large. You find a large thing and turn it into an adjective. Gargantua, the giant hero of a book by Rabellais, gave us gargantuan. The Biblical monster Behemoth gives us behemothic. The Himalayas give us Himalayan and so on and so forth. But none of these words fit. They are all bulky, and the tennis match is long.
My best suggestion would be jörmungandrian. Jörmungandr is a snake from Viking mythology which grows so long that it encircles the earth and ends up biting its own tail. As I mentioned in a previous post the circumference of the earth is 24,901.55 miles, so Jörmungandr is very long indeed.
Well, Dumbstruck in Delaware, I hope that helps. And remember: having a bigger vocabulary doesn't necessarily make you a "better" person, what really matters is whether you can use that vocabulary to negotiate with tennis-obsessed cannibals.