If there's a restaurant out there that actually serves crow, Citi analyst Mark Mahaney might not mind a plate of it.

Mahaney upgraded shares of web-based reservations specialist OpenTable (Nasdaq: OPEN) this morning, less than three months after he downgraded the stock at a much lower price point.

Back in June, the analyst took the stock down a peg -- from "buy" to "hold" -- after it hit his $45 price target. What brings Mahaney back to the table now, with the stock closing over the weekend at a price 26% above his late June exit?

According to Mahaney, the story has changed. He sees improving trends, but that's not a recent development. The company posted a healthy 37% spike in quarterly revenue five weeks ago. Despite macro concerns over the state of dining out, OpenTable's top line has been accelerating during the recession. In other words, this isn't a new development.

Mahaney also sees OpenTable as a growing play on smartphone adoption, but that's no "stop the presses" event, either. I've been booking dining reservations through OpenTable's application for Apple's (Nasdaq: AAPL) iPhone for more than a year.

Mahaney's third salient point is the game-changing potential of OpenTable's Spotlight initiative -- but he's late for that bandwagon, too. Merrill Lynch's Justin Post upgraded the stock last month based largely on Spotlight.

Spotlight is OpenTable's program -- currently being tested in two cities -- where folks can buy discounted vouchers for popular eateries. The model has propelled market leader Groupon toward a 10-figure valuation in venture-capital financing rounds.

Margins in this space can be pretty juicy, but the market's also getting pretty crowded. Everybody seems to be playing the Groupon card. Travelzoo (Nasdaq: TZOO), The Knot (Nasdaq: KNOT), and Yelp have all dived into this niche, and they won't all succeed.

OpenTable will face challenges -- and not just from Yelp. OpenTable has working relationships with 12,250 North American restaurants and another 1,878 abroad, but won't offering a single city-specific deal for a particular customer alienate its base? If OpenTable becomes a site known for both dining discounts and online reservations, won't it tempt eateries that aren't discounting to seek a rival service? Before Groupon's rise awakened the sector, OpenTable had no inclination to follow in the footsteps of dining loyalty specialist Rewards Network (Nasdaq: DINE). It does occasionally offer more points in its rewards program for participating restaurants, but that won't rattle the system as dramatically as half-off vouchers for a new client hungry for first-time diners.

This doesn't mean that I'm wavering in my bullish conviction. OpenTable has more than doubled since I recommended it to Motley Fool Rule Breakers newsletter subscribers last summer. It's holding up well against competitive threats and accelerating growth is always a welcome omen. The company has done nothing but blow analyst estimates out of the water with every passing quarter since last year's IPO.

However, when you're eating in a crowded restaurant with reformed bears, it's always nice to know where the exits are -- just in case the kitchen is fresh out of crow.

Have you ever used OpenTable for a restaurant reservation? Share your thoughts in the comment box below.