distinguish all these players who are moving around and shifting positions all the time.

KOPP: It's pretty complicated stuff created by some data algorithm engineers. They were originally based in Israel. They had worked on similar optical tracking projects for the military - essentially, missile tracking. And they had an interest in sports so they developed this system to track soccer - football players, rather than tracking missiles for the military.

BLOCK: OK, well, so far in World Cup 2014, which player has run the longest distance through the round of 16?

KOPP: So two of the top three are Americans. So Michael Bradley from the US team has covered 34 miles in those four games, and in yesterday's match against Belgium he covered 10.4 miles.

BLOCK: In just one match?

KOPP: Injust one match. And we can break down that distance to know - was he running, jogging, sprinting? He actually had 65 sprints throughout the course of the game as well. So we can take this data and break it down to a very granular level.

BLOCK: So you said two of the top three were U.S. players.

KOPP: Yeah, Jermaine Jones was number three. He covered 29.6 miles in the four matches thus far.

BLOCK: And who's third?

KOPP: Marcelo Diaz from Chile.

BLOCK: And in terms of speed, who's been the fastest runner at the World Cup?

KOPP: So the fastest runner has been Junior Diaz from Costa Rica. He reached a max speed of 21 miles per hour.

BLOCK: No kidding.

KOPP: For the U.S., Fabian Johnson was the fastest at 20.5.

BLOCK: I