The patent cliff has been the biggest challenge facing the pharmaceutical industry as of late. It's already taken a huge bite out of some big pharma firms' financials: Top drugmaker Pfizer (NYSE:PFE) has seen its sales taken down this year thanks to the patent loss of former top-selling compound Lipitor, which has lost around half of its revenue year-over-year through the first nine months of 2013. In 2014, two companies are facing even bigger potential losses than Pfizer.

Who's up to bat in the new year? Look no further than Eli Lilly (NYSE:LLY) and AstraZeneca (NYSE:AZN). These two companies are facing tough times ahead with the loss of patent protection on their respective star drugs Cymbalta and Nexium, and the resulting fallout could cost the companies billions of dollars of revenue -- and investors a big hit to their portfolio.

But can Eli Lilly and AstraZeneca beat the patent cliff next year? Find out in the video below, as Fool contributor Dan Carroll takes you through the daunting hurdles these two big pharma firms face -- and whether they can deliver for investors regardless of the challenges ahead.