Before you lock in your 2018 World Cup bracket picks for the knockout stage, which is now down to four teams, you need to see what European football expert David Sumpter has to say. 

Sumpter is an applied mathematician who wrote "Soccermatics," the book that shows how math works inside the game. Together with experienced analysts, Professor Sumpter developed the powerful Soccerbot model.

The Soccerbot reads current odds and all team performance data, calculates key metrics and predicts upcoming matches. In the two-and-a-half seasons since it was born, the Soccerbot is up 1800 percent on bookmakers' closing odds. That's right -- 1800 percent!

Now the Soccerbot, which analyzed every quarterfinal and potential matchup moving forward, has locked in its picks for the semifinals and final

One surprise: the model says France, the odds-on favorite at 2-1 to win it all, falls to Belgium in the semis. The model gives Belgium a 53 percent chance of beating the French.

Sumpter's optimal bracket has also identified its World Cup champion. Nailing this pick is the key to winning your World Cup bracket pool.

So what is the optimal bracket for the World Cup challenge? And who is crowned champion?... Join SportsLine here to see which teams you should be all over in your World Cup brackets, all from the model that's returned an incredible 1,800 percent profit on bookmakers' closing odds.