Ford's hot-selling Fusion Hybrid has stolen lots of sales from Toyota in 2013. But now Ford's factory is struggling to keep up with demand, and that could cost the Blue Oval. Photo credit: Ford Motor.

Ford (NYSE:F) has had a solid lead over Toyota (NYSE:TM) in the U.S. market for some time now, and it has gained market share at Toyota's expense in 2013. But July's sales numbers included a surprise: Toyota nearly closed the gap for the first time in ages.

How did that happen? There are a few different factors at work, ranging from Toyota's aggressive moves to reverse its decline in U.S. market share to Ford's ongoing struggles to make enough of its hot products to meet demand. So was July a fluke, or is Toyota about to surge past Ford? In this video, Fool contributor John Rosevear digs into the numbers and gives his take on Ford's prospects for staying ahead of its biggest Japanese rival in the coming months.